Original subtitles

NARRATOR: They're watching you.

More than 5,000 satellites circle the Earth.

Every day, they uncover new, mysterious phenomena that

defy explanation.

The blood code of the samurai.

They would behead people.

They would boil them in oil for even

a simple infraction of the code.

NARRATOR: The mystery structures that transformed the world.

HORTON: They're enormous.

It's just staggering the effort

and engineering to build this.

NARRATOR: And Nazis, knights, and vampires

in the forests of Poland.

They've been decapitated and their skulls

buried between their legs.

NARRATOR: Baffling phenomena. Mysteries from space.

What on Earth are they?

**

**

The county of Yorkshire, England.

A land of rolling moors and hills.

Archaeologist Mark Horton is here to investigate a strange

satellite image taken over the region

on October 2nd, 2019.

HORTON: It shows a series of circles,

almost as if the landscape has

got some horrible disease over it,

like sort of pustules on the face of the ground.

NARRATOR: A LIDAR scan of the site reveals

the weird pimples are up to 100 feet in diameter

and appear to be manmade.

MORGAN: This is fascinating. The LIDAR image

almost looks like wasps' nests.

This is a really confusing thing to see.

I've not seen anything like this.

HORTON: As an archaeologist,

when you see mounds, one immediately

assumes that they are burial mounds.

But they're just too regular, uh,

and too many of them to suggest that.

NARRATOR: What's more, a wider search of

the region using Maxar's SecureWatch technology

reveals dozens of other

clusters of the strange giant mounds.

JOYCE: One of the extraordinary things is the sheer

number of them that I see across the landscape.

It's really weird to see this type

of pattern replicated in so many different areas.

**

NARRATOR: Horton heads for a group of mounds

in the west of the county.

HORTON: So this is it.

They're totally different on the ground to

what they look like from the air.

They're enormous!

NARRATOR: Horton counts around 50 of the bizarre features,

covering almost two million square feet of land.

HORTON: Now I'm up here,

I can see just how regimented all these mounds are,

literally marching across the landscape.

Just think of the human effort of constructing these.

NARRATOR: It's not just the scale and pattern of the mounds,

but their shape that baffles the archaeologist.

There seem to be really two types of mounds.

Some are sort of flat platforms,

and some that are like doughnuts.

It's really a mystery.

NARRATOR: Horton returns to the wider images for clues.

So looking at these

satellite images,

I can see this group on the Yorkshire moors

seems to have buildings next to them.

Probably the best thing is for me to check those out.

NARRATOR: Horton makes his way to the North York Moors,

550 square miles of heathlands

carved out during the last Ice Age.

**

These must be the buildings I saw on the satellite image.

They're really quite substantially built,

but it's difficult to see actually what they are.

NARRATOR: A clue to the purpose of the crumbling

ruins is etched deep into the hillside below.

Looking along that direction, it's a straight line.

And it's a straight line running around the hills,

actually, as far as the eye can see.

I mean, this to me suggests it's a railway line.

NARRATOR: What's weird is that while the ghost

railway station is near the mounds,

it is miles from any known town or city.

If it's a railway, then we have industry, because the only

reason why you'd want to build

a railway up here is to move heavy materials around.

NARRATOR: A half mile past the abandoned railway

station sits another strange echo of Britain's

industrial past.

That's just amazing!

I mean, it's almost like a medieval cathedral

in its scale.

NARRATOR: 16 giant arches around four stories high

stretch for 300 feet along the hillside.

It's just staggering, the effort

and engineering to build this.

There's some evidence up there they've been heated.

You can see the different color in the stone.

They were built to withstand huge amounts of heat.

NARRATOR: Horton believes these are giant kilns,

more relics of what appears to be

a sprawling 19th-century industrial landscape on

these hills,

one that explains the clusters

of giant pimples revealed from space.

These mounds, I think, are the remnants of mining,

and what we're looking at are shafts

that were sent down to extract the oil.

NARRATOR: Around 150 years ago,

vast numbers of people flocked to these remote moorlands,

drawn by something hidden beneath the earth.

HORTON: This is really interesting.

It suggests that what was actually up here was

really valuable.

It's all a bit of a puzzle.

NARRATOR: Coming up, how the weird mounds

and ruins changed history.

What we've got is a really unexpected discovery.

NARRATOR: And the tale of the Sultan,

the spy, and the exploding trains.

This was the origin of all

of the conflicts in the Middle East that we see today.

NARRATOR: Mark Horton is in Yorkshire

in the north of England,

investigating clusters of strange mounds

surrounded by an array of monstrous,

decaying industrial buildings.

Why would anyone want to come up here to construct these

in such an inhospitable place?

NARRATOR: The archaeologist has discovered the mounds are

the remains of unusually shaped mineshafts.

A nearby hillside yields a clue

to what drew so many prospectors here.

[grunting] Look at this,

coming out of the hillside.

Oi! These rocks are red.

This is ore, this is ironstone.

It's a slightly orangey-red color from the iron,

just like rust on an iron object.

NARRATOR: The presence of iron here and the age of the ruins

suggest these mines played

a key role in one of the most extraordinary events

in human history.

HORTON: This is all about the exploitation of

the vital ingredient for the Industrial Revolution.

Because with iron ore, you make the modern world.

NARRATOR: the Industrial Revolution,

which begins in Britain in the mid-18th century,

transforms a world reliant on farming into one of mills,

machines, and manufactured goods.

JANULIS: This is one of the time periods in which

society progresses so rapidly,

you blink your eye, and you miss it,

and suddenly we're entirely different.

NARRATOR: In 1712, the British invent

the first commercially available steam engines,

enabling miners to dig deeper, machines to work faster

for longer,

and generating huge wealth for the nation.

But while this extraordinary growth

was powered by coal and steam,

it was built on iron.

JANULIS: For a nation that's marching towards

an industrialized society,

this stuff was a mineral lottery ticket.

NARRATOR: Fueled by the demand for bridges, ships,

buildings, and railways,

between 1700 and 1850, British iron production

increases from 12,000 tons a year to over two million,

and the hills and moorlands of Yorkshire become

the focus of an incredible sequence of events.

In 1854, the English discovered large amounts

of pure iron ore deposits under the moors.

This kicked off a booming economy

as miners rushed into the region.

NARRATOR: To extract the precious ore,

prospectors turned to an ancient and highly dangerous

mining technique first used by monks in the 12th century

called a bell pit.

MORGAN: The extraction process involved dropping a shaft down

into the vein,

and then you would work that area until you created

basically a bell-shaped dome.

JANULIS: The non-iron ore would get dumped on the sides.

That's why we have these weird mounds with a hole right in

the middle, dotting certain areas on the moors.

NARRATOR: As more and more rock is pulled from the ground,

giant kilns are built nearby to process the iron ore.

By drying it out with intense heat and by expelling

the carbon dioxide, a much

purer form of ore could be obtained,

which could then be loaded onto the trucks and taken by

railway to the blast furnaces.

NARRATOR: Across Yorkshire, the bell pit mining technique

is used to extract both iron and coal.

In 1856, an Englishman named Henry Bessemer combines both of

these minerals to create

a process that has a dramatic impact on almost every city

and industry on our planet.

The Bessemer process was a way of taking iron ore slag,

putting it into a furnace, and refining it, and the process was

revolutionary, because it

suddenly made steel production affordable.

NARRATOR: Thanks to the Bessemer process,

steel, for centuries almost exclusively used for making

weapons and ornaments, could be

mass produced for the first time.

HYMEL: That's a real game changer,

and the place where this new steel really

makes a difference is the United States.

We're suddenly capable of doing things

that we would never have dreamed possible,

like skyscrapers that are 20, 30, 40,

50, 100 stories tall.

HYMEL: Some of the most iconic buildings and structures in

the United States are all a result

of the Industrial Revolution and the use of steel.

[train whistle blowing]

NARRATOR: Steel also builds the railways

that open up the American West,

helping transform the country into an economic superpower.

**

Today, the unique industrial landscape that helped

spark this revolution is fading to ruin,

but its legacy lives on in every corner

of the modern world.

KOUROUNIS: It's really incredible how we can look down

from space on this series of events

that happened so long ago that changed the world in

such profound ways.

NARRATOR: Coming up, the wrath of the ancient super warrior.

KOUROUNIS: If you were to disrespect the leaders,

punishment was swift and harsh.

NARRATOR: And the 200-foot-long sand skeleton.

It looks like some creature that

died and withered away in the desert.

NARRATOR: September 2019.

An aerial image shows a disturbance in

the sands on the coast of Japan's Shikoku Island.

The only way I can describe this is someone has taken

a gigantic rubber stamp and slammed it into the ground,

and it's left this impression behind.

It's so bizarre.

The mystery 120,000-square-foot structure

overlooks the Inland Sea, and to military historian

Martin Morgan, that's a clue.

This is an extraordinarily important body of water.

When I see monumental construction projects

near a beach,

I suspect that the military is involved.

NARRATOR: The structure's location could mean

it's connected to one of

the most astonishing plans in military history,

Operation Downfall.

MORGAN: Operation Downfall was America's plan to invade

the Japanese home islands in late 1945, early 1946.

Maybe what we're looking at here was something that was

built in a scramble to prepare for the American invasion.

[explosions blast]

NARRATOR: In 1945, at the end of five years

of brutal conflict, Japan is on its knees.

Operation Downfall is to be the hammer blow,

a two-pronged amphibious assault

on Japan on an unprecedented scale.

Operation Downfall would involve troop numbers

measured in the millions.

Just one of the two invasions would have been

more than twice the size of the D-Day invasion.

NARRATOR: The first part of the plan, code-named

Operation Olympic, would see an armada of 400 destroyers

and an astounding 42 aircraft carriers attack Kyushu,

the island to the south of the structure in the image.

[shouting]

But the U.S. military knows that even this mega fleet

may not be enough to defeat the Japanese.

Imperial Japanese military forces were

the toughest opponent that the U.S. military has ever faced.

[shouting]

We're looking at potential suicide squads attacking

invading troops and civilians

fighting with sticks if they had to, to the death,

and that's what made Operation Downfall very,

very dangerous for the Allies.

NARRATOR: Estimates suggest that the invasion was to be

the bloodiest chapter of World War II,

costing a staggering 11 million lives.

We had every reason to expect that every last man,

woman, and child would be a threat.

President Truman ultimately authorizes the use of

the atomic bomb, with this sober

recognition for the fact that an invasion was going to be

extremely costly.

And what a terrible decision to have to make as a leader.

NARRATOR: Yet archaeologists familiar with Japanese culture

reveal the mystery structure dates from

another violent period in this country's history.

BELLINGER: The shapes look symbolic.

Looking really closely at this structure, the figures actually

represent the classic coin of the Edo period,

corresponding to the height of samurai rule in Japan.

NELSON: The question is, why would anybody

create a giant image of a coin?

NARRATOR: Analysts turn to the history

of the samurai for clues.

There was a period several centuries ago

when there was great unrest and turmoil,

and fiefdom leaders set about creating a class

of warriors that would create order out of chaos.

These were known as samurai warriors.

[horse snorts]

NARRATOR: The first samurai of the 10th century

operate as small bands of warriors for hire.

Yet over time, they organize themselves in groups led by

warlords and begin to command political as well as

military power.

These guys were true warriors.

They were fit, they were smart, and they were well armed.

They grew to such prominence by the 12th century,

they co-ruled Japan with the emperor.

NARRATOR: The samurai's primary weapon, the katana,

is forged from around 1,000 layers of folded steel.

Their 41-inch blades were at times tested on live

criminals as a gruesome method of proving

their strength and sharpness.

It was much more than a weapon to the samurai.

It was thought to harbor his very soul.

It was brought into the delivery room when

a samurai was born,

and it was the last item laid by his side as he died.

NARRATOR: It is the samurai's brutality off

the battlefield rather than on it

that could explain the structure in the image.

What defines the Edo period was

the strictness with which samurai went about

ensuring order in Japan.

It was really a very brutal process.

NARRATOR: In feudal Japan, 90% of the population are peasant

farmers or trades people,

who must give up half of what they earn in tax to

the samurai.

They live in constant fear of their warrior masters.

If you were to upset or disrespect the local

samurai leaders,

punishment was swift and harsh.

ALBERTSON: They would behead people.

They would boil them in oil.

And all of those for even

simple infraction of the social code.

NARRATOR: Local oral histories suggest

that this reign of terror led to the construction

of the strange sand coin visible from space.

Legend states that this was built when

the local samurai leader was coming to the area,

but the locals were so poor that they had no gift to offer.

So they make him a tribute out

of the only thing they have available -- sand.

NARRATOR: 400 years ago, local peasants created

the giant coin to buy their lives.

Over the centuries, it is meticulously maintained as

a monument to their ingenuity and their desperation.

Coming up, desert carnage.

The man who took on an empire.

A lesser man would not have carved their name

into time memoriam the way that he did.

NARRATOR: And how to bury a vampire.

This idea that the dead might come back again

was very, very scary.

NARRATOR: From 420 miles over the Arabian desert,

a satellite captures an anomaly in the seemingly

endless sea of sand below.

In the middle of the image, there's something that forms

a distinct shadow,

something very dark and blocky.

It almost looks like the skeleton

of some creature that died and withered away.

There's no obvious explanation as to how

a structure like this ended up in the Saudi desert.

NARRATOR: The mystery objects sit near a strange

Y-shaped pattern etched into the dunes.

The curves here look like thoroughfares.

Something was moving along these lines.

This looks like a railway.

We're looking at an abandoned train wreck.

NARRATOR: A train wreck in the middle of the desert is

intriguing enough,

but what's astonishing is who put it there.

MORGAN: Historical records show that we're looking at one of

the trains that was destroyed by Thomas Edward Lawrence,

also known as Lawrence of Arabia.

NARRATOR: The 1962 movie "Lawrence of Arabia,"

starring Peter O'Toole,

is widely regarded as one of the greatest films ever made.

But when it comes to the story of the man who inspired it,

the truth really is stranger than fiction.

The tale begins in 1909,

when the Sultan of the Ottoman Empire orders construction of

the Hejaz Desert Railway

connecting Istanbul with the holy city of Mecca.

PAVELEC: It was a method for the Ottoman Empire to be able

to maintain centralized control over the Arab lands

at the time.

This project was ambitious, to say the least,

because normally this is sand traversed only by camels.

NARRATOR: To construct the Hejaz,

the Ottomans lay down almost 1,000 miles of track,

bridges, and tunnels through some of the most inhospitable

terrain on Earth.

The steam railway was a triumph of man

and technology over the ravages of the desert.

The Hejaz Railway was one of

the greatest civil engineering accomplishments

of the 20th century.

NARRATOR: The Hejaz also provides the Ottoman Sultan with

a vital transport link for his three-million-strong army.

So when he sides with Germany during the First World War,

the line becomes a prime target for the British military.

It was capable of bringing whole troops

and armies across the desert with munitions.

MORGAN: And the result of that is the British

begin to make war against the Ottomans.

NARRATOR: The British know that to defeat the Ottomans,

they must persuade local Arab forces to help them destroy

the Hejaz Railway.

Up steps British archaeologist, army officer, and spy

Colonel T.E. Lawrence.

Lawrence is the perfect man, because he understands

not just the terrain and the area,

but he understands the people.

He speaks the languages, he's very favorable towards

the Arabs, and the Arabs are also favorable towards him.

NARRATOR: In 1916,

Despite being vastly outnumbered by the sultan's forces,

Lawrence and the Arab rebels begin

a daring campaign of sabotage in the desert.

Lawrence turns out to be

a very effective leader of guerilla warfare.

[explosions blasting]

PAVELEC: They would blow up rolling stock.

They would sabotage the steam engines.

They'd break down the Ottomans'

ability to maneuver and move around.

At one point, Lawrence captures a train with

his men so short on weapons

that some of them could only throw rocks at the enemy.

NARRATOR: The key to Lawrence's success was

a tactic he called scientific shattering.

He believed that, in warfare, if you kill one man,

you just remove a man from commission.

But if you wound a man,

you have to tend him.

You have to give him medical care.

This is exactly what Lawrence did to the railway line, because

he perfected this technique for blowing up a bridge

without destroying it.

NARRATOR: By attacking Ottoman forts

and damaging sections of the railway,

Lawrence forces the sultan to repeatedly deploy vital

resources to far-flung parts of the desert.

It's a brilliant tactic.

[explosion blasts]

He was able to keep harassing the Ottoman Empire until they

simply just could not fight anymore, because they were

exhausted through attrition.

NARRATOR: In one month of 1918 alone,

Lawrence and the rebels blow up 25 sections

of the Hejaz Railway,

creating a 600-mile-long trail of destruction

and pinning down thousands of Ottoman troops.

Their dreams of moving troops and munitions across

Saudi Arabia vaporized in that desert air

thanks to T.E. Lawrence.

NARRATOR: After their defeat in the Great War,

the Ottoman Empire disintegrates,

but the Arab rebels are poorly rewarded for

the blood they spilled for the British

in the desert sands.

At the end of the war,

the French and the British divide up Arab lands and begin

to siphon off all the oil.

This creates a backlash that is really the origin of all

of the conflicts in the Middle East that we see today.

NARRATOR: In 1935, Lawrence is killed in

a motorcycle accident in the British countryside.

Yet even today, the legacy of his incredible

exploits in the Arabian Sands survive, visible from space.

MORGAN: That's why a movie's made about him.

A lesser man would not have carved their name

into time memoriam the way that he did.

NARRATOR: Coming up, vampire graveyards.

People would hear the living dead under the ground.

NARRATOR: And Geronimo, the giant flying rodent.

I don't think I'll ever look at the beaver the same way.

NARRATOR: April 2016.

Archaeologists began an aerial survey of

countryside near the town of Pieniezno, Poland.

A laser scan of the forest below peels back

the canopy to reveal a cluster of medieval houses

lost to history.

But it's what's hidden in the center

of the ancient village that really intrigues historians.

WALTERS: I can see some roads.

I can see some fields.

There is something that actually is quite perplexing.

It's this kind of cube-like mound.

It just stands out like a sore thumb.

What is it, and why is it

so different from everything else around it?

NARRATOR: To historians, the shape of the mystery

structure suggests it could have a macabre origin.

This big doughnut feature could possibly

be a burial mound,

and that's intriguing, because if this is a burial mound,

it could be connected to a recent

discovery very close by that's not a little gruesome.

BELLINGER: Just across the way, archaeologists dug up

four bodies, and they're amazed

to find that they've been decapitated

and their skulls buried between their legs.

NARRATOR: Experts believe the heads were

purposefully removed after death in

an attempt to stop the cadavers

from rising from the grave.

Typically, we don't find bodies in this

kind of orientation, except in speculation of vampires.

It's really easy for us today to laugh

at this whole idea of belief in vampires.

You've got to remember at

the time, people thought they were real.

NARRATOR: The belief in vampires could have begun

in medieval times when gases from bloated,

plague-ridden corpses would force blood out of the mouth,

making it look like they had been feasting on human flesh.

HORTON: As the gases built up,

it would literally pop like a balloon.

People would hear the ground popping under their feet,

and this gave the idea that the living dead was down there

under the ground.

NARRATOR: The very real fear of the undead led to

corpses being buried with sharpened sickles at

their necks.

This idea that the dead might

come back again did not seem superstitious.

It was very, very scary.

We've seen examples where wooden stakes were driven

through the skeleton to pin it to the ground.

Maybe the structure could be some kind of grave site,

possibly even containing the sort of mutilated skeletons

they found across town.

NARRATOR: Yet further examination reveals the site

in the image has a different origin.

SZULGIT: Upon excavation,

archaeologists find weapons, palisades, ramparts.

This was obviously some kind of fortification.

NARRATOR: The studies reveal that the long-buried

fortification was once a seat of power of

a wealthy and mysterious Catholic military order,

the Teutonic knights.

RUBEN: These were not knights

like you'd see in a Disney movie.

These knights were actually ruthless, brutal,

savage murderers.

NARRATOR: The Teutonic Knights were founded in 1198 A.D.

to help retake Jerusalem from the Arabs during

the Crusades.

WALTERS: In order to become a Teutonic knight,

you had to swear that you would be chaste,

so there was no sex for your Teutonic knights.

But they compensate for their lack

of social interaction by their warrior prowess.

They're very fearsome.

NARRATOR: When they return from the Crusades,

the Teutonic knights begin an even bloodier campaign,

waging a religious war for the high Duke of Poland

in Prussia.

He enlists them to come and act

effectively as mercenaries in quelling paganism

throughout Prussia.

NARRATOR: Over the following 50 years,

the knights put tens of thousands of pagans who refuse

to be baptized to the sword.

HUNT: They were very brutal in how they suppress the people.

Nobody wanted to mess with the Teutonic knights.

The Teutonic knights use this campaign to effectively

assert their dominance throughout the whole of Prussia.

NARRATOR: Following their victory

against the Prussian pagans,

the nights grow in strength and embark on more

military campaigns.

They use the plunder from these wars to construct castles

across Eastern Europe,

including the one revealed by aerial imaging.

WALTERS: I mean, what more does your average

night need than some gold in a castle?

They'd become this very powerful,

almost, you know, nation, state-like force in themselves.

NARRATOR: As the years pass, the knights' power fades.

But in the 20th century,

the emblem that adorned their tunics and shields

returns as an icon of pure evil.

And that is the very famous black and white Teutonic cross.

It becomes the Iron Cross famously that we associate

with the Second World War from the German armed forces.

NARRATOR: The Nazi use of the knights' cross

is part of an attempt to mythologize

themselves as a continuation of the Teutonic order's

battle to spread Christianity.

The Teutonic knights got a very bad name because of

the way in which they were appropriated by Nazi propaganda.

NARRATOR: Seven centuries before the Nazis rise to power,

the Teutonic knights constructed the castle in the image

using the spoils from their own genocidal wars.

After being swallowed by the earth,

it is rediscovered once more from the skies.

There's so many other mysteries out there waiting to

be solved, and now, thanks to things like LIDAR,

are we have the tools to begin solving them.

NARRATOR: Coming up, the day they bombed Idaho with beavers.

It was basically the world's first beaver delivery service.

NARRATOR: Summer 2018.

Aerial images show an unfolding disaster as

the Earth burns.

If you ever find yourself in

the path of one of these wildfires,

it can be absolutely terrifying.

It's almost like a vision of hell.

NARRATOR: In the United States alone,

some 58,000 wildfires devastate an area four times

the size of Yellowstone National Park.

But as a drone scans

the charred remains of Idaho's Sawtooth National Forest,

it captures an anomaly.

We're looking at a devastated landscape,

but then down in the valley is this miracle.

Trees, plants, vegetation all gone,

except for this one, really lush green patch.

NARRATOR: The snaking green oasis appears to follow

the course of a river.

In other places, the wildfire has burned right over the river,

but this one spot was completely skipped over.

So what is it about this area that kept it protected?

NARRATOR: Satellite images identify other similar areas

that have been spared from fiery annihilation.

Scientists look far and wide to figure out what it is that

connects them, and they find

that they all have one thing in common -- beaver dams.

It turns out beavers are elite firefighters,

and they can stop an inferno in its tracks.

NARRATOR: The secret to the beavers' firefighting

heroics lies in their chisel-shaped teeth.

They enable the 60-pound rodents to gnaw

through up to 200 trees each year,

creating dams that can stretch for half a mile,

irrigating hundreds of acres of land.

The dams and the ponds can get so big that some

of them can be seen from space.

KAYS: By spreading out the water,

it encourages the plant growth throughout the area

and basically turns it into

a giant sponge that isn't gonna burn when a fire comes through.

NARRATOR: The small sliver of life

discovered in the charred hills of Idaho

only exists because of a curious quirk of history.

Beavers haven't always been appreciated

as the superheroes that they are.

In fact, they were almost hunted to extinction

for their pelts.

Beavers played a surprisingly important role in the early

frontier days of North America.

All across the United States and especially up into Canada,

beaver pelts were the number-one industry.

NARRATOR: Between the 16th and 19th centuries,

the fur trade fuels a mass slaughter of the beaver

population that sees their numbers

plummet from 400 million to just 100,000.

This crash of the beaver population had, you can imagine,

all kinds of effects on the rest of the forest.

The landscapes dried up, and that made it very,

very vulnerable to fires.

NARRATOR: During the 1940s,

authorities decide to repopulate Idaho with beavers.

It leads to a truly bizarre experiment.

So the question is, how do you reintroduce a beaver?

Well, to get to some of these remote landscapes,

they literally bombed Idaho with beavers.

NARRATOR: In 1948, scientists put an elderly

beaver called Geronimo into an airplane,

take to the skies over Idaho,

and then toss him out of the side.

DENNIE: Well, they parachuted the beaver out of a plane in

a box, and the door would open, and the beaver would come out.

It was basically the world's first beaver delivery service.

NARRATOR: Geronimo the parachuting beaver

is followed by dozens more flying rodents.

Imagine yourself in Idaho, and you look up,

and you have beaver parachuting down on you.

Man, that would have been weird.

CERVENY: It actually worked.

We were able to reintroduce beavers,

and they start to re-establish the original environment.

NARRATOR: Today, thanks to the efforts

of Geronimo and others like him,

an estimated 15 million beavers across the U.S.

form an astonishingly effective force of

natural firefighters

revealed from the skies.

DENNIE: I have a new appreciation for the beaver

and for beaver dams, and I don't think

I'll ever look at a beaver the same way.