JustWatch
S01 Episode 1
Secrets of the Rock
A hidden, subterranean city built within the Rock of Gibraltar was an immense fortress to control the seas during World War II, and new discoveries reveal the secrets of a long-lost chamber with evidence of high-stakes espionage.
45 mins · Thu, 17 Oct 2019
S01 Episode 2
Mystery of the Lost Labyrinth
A strange, centuries-old labyrinth built into an abandoned quarry was built by an eccentric millionaire, and no one knows why; but now, a new excavation into this mysterious 9,000-foot tunnel system might finally reveal its dark secrets.
45 mins · Thu, 24 Oct 2019
S01 Episode 3
Secrets of the Terror Tunnels
A vast system of tunnels built almost three thousand years ago was the site of the greatest battles of antiquity, and these disorienting passages could be the deadliest weapon in war; experts reveal what made this underground world so terrifying.
45 mins · Thu, 31 Oct 2019
S01 Episode 4
The Renegade's Lair
A strange underground system known as the Black Cave was home to an infamous nobleman on the run from the law; today, experts investigate the secrets he left here to discover new parts of this mysterious network.
45 mins · Thu, 7 Nov 2019
S01 Episode 5
Cave of the Body Snatchers
An eerie system of underground vaults in Scotland was once the hideout for thieves who stole newly-buried bodies and sold them; today, experts are excavating these rubble-filled caves to reveal the secrets of what these bandits left behind.
45 mins · Thu, 14 Nov 2019
S01 Episode 6
World's Biggest Labyrinth
The world's biggest labyrinth is a 1,553-mile cave system that's home to some of history's darkest mysteries, and new discoveries at this strange place reveal the long-lost secrets of Nazi occupation, Soviet revolution, and Cold War subterfuge.
45 mins · Thu, 21 Nov 2019
S01 Episode 7
Treasures of the Lost Mine
Caverns hidden deep inside a remote mountain are home to a precious mineral found nowhere else on earth, and experts and treasure hunters use cutting-edge tech to follow rumors of a mysterious long-lost mine in search of a payday.
45 mins · Thu, 5 Dec 2019
S01 Episode 8
Ghosts of the Hell Maze
A labyrinth of tunnels in the French countryside has served as a secret hideout during wartime for centuries. On its walls, experts have discovered the final confessions of soldiers who fought here during one of the deadliest days of World War I.
45 mins · Thu, 12 Dec 2019
S01 Episode 9
Conspiracy in the Buried City
A buried ancient city hidden five stories underground, and to keep its location secret from invaders, its residents devised an ingenious trick; experts reveal what it was, and using the latest tech, they reveal the truth behind this strange place.
45 mins · Thu, 19 Dec 2019
S01 Episode 10
Curse of Cannibal Caves
A mysterious cave system is home to some of the oldest human remains ever discovered, and today, the explorers and researchers investigating this site are uncovering shocking evidence of cannibalism among its Ice Age denizens.
45 mins · Thu, 26 Dec 2019
