Some disguises hide an individual, others conceal an entire operation. A CIA vaccination campaign masks a global manhunt for the world's most wanted terrorist. Sometimes the safest place to hide a secret is right out in the open.

Some targets are taken by force – others require a game of cat and mouse played out across continents and years of relentless chase. While the prey changes, the pursuit never does.

Before they became instruments of war, they sounded like impossible ideas. An American medical student develops a closed-circuit rebreather that allows Allied frogmen to slip beneath enemy harbors without a single bubble.

Every spy needs a cover story – and the best gadgets have one, too. In the jungles of Vietnam, the U.S. military built sensors that could sniff out hidden enemies. Sometimes the most dangerous weapon in the room is the one nobody realizes is there.

Some strongholds are built to defend a nation, others to survive its darkest hour. From deception to survival to espionage, these hidden sites reveal the lengths nations go to when the stakes couldn't be higher.

Some deals are made to announced headlines, while others are steered in the shadows. While the fingerprints may be hidden, the consequences of every deal leaves a lasting mark.

Some targets are taken by force – others require a game of cat and mouse played out across continents and years of relentless chase. While the prey changes, the pursuit never does.

Sometimes when governments can't negotiate their way to victory, they steal it. When the KGB sets its sights on a NATO missile, they enlist a smooth-talking German playboy armed with only a wheelbarrow, a carpet, and a postage stamp.

Some missions are so risky, they're denied before they even begin. These operations are proof that the most dangerous missions are often the most unthinkable.

To outmaneuver the enemy, you have to sell the illusion. An FBI agent goes so deep undercover he's best man at a Mafia wedding, while the Stasi deploys a covert network of charmers across borders to win trust and steal secrets.

In Operation Halyard, villagers and resistance fighters built an airstrip by hand to spirit stranded airmen out of Nazi territory, while Operation Mount Hope saw American forces steal a Soviet helicopter from the African desert under cover of darkness.

David Duchovny takes us into the long-spun elaborate tales governments have employed to blanket their boldest missions, showing us how the illusion works – or until it doesn't.

Follow the secretive flights of Project Argus, that sent nuclear warheads into space to test whether radiation could cripple Soviet weapons, while Operation LAC covertly released chemical agents over American communities to simulate biological warfare.

Behind official policy often stands unofficial actors. Discover the audacious operations of Red Cell.

A stranded American pilot in Vietnam is rescued through a code built around familiar golf courses, while Navajo Code Talkers transmit messages that help turn the tide in the Pacific during WWII.

From a British scheme to launch airborne balloons against Nazi Germany, to American bats fitted with incendiary devices, to a covert effort to manipulate monsoon rains in Vietnam.

A French Resistance operative hides explosives in baguettes to cripple a Nazi factory, an American soldier parachutes behind enemy lines to destroy critical supply routes, and Ukrainian forces deploy AI-guided drones to strike a Russian bomber fleet.

David Duchovny exposes a clandestine nuclear blast set off deep below Mississippi soil, and secret experiments conducted on citizens in the New York subway system.

Step inside the hidden areas where history was steered in secret. From Churchill's wartime bunker — complete with a direct line to FDR concealed inside his private bathroom — to a Soviet weapons base in the desert.

In the razor's-edge theater of global brinkmanship, the world has come closer to annihilation than most ever knew.