Easter Island: Hundreds of years ago, a small group of Polynesians rowed across the open sea, navigating by the stars. But when - and why - did they leave their native land? (S1, ep 11)

Nostradamus: The prophecies of Nostradamus, from the French Revolution to the rise of Adolf Hitler, have long piqued interest - and according to him, the world will end in 3797. (S1, ep 12)

Military vs. UFOs: The team examine incidents of alleged conflicts between the US Air Force and the RAF, and asking whether these encounters have been covered up. (S1, ep 11)

Aliens And Evil Places: Experts investigate creepy places associated with death. Could otherworldly connections be responsible for strange disappearances and suicides? (S3, ep 10)

Aliens And The Creation Of Man: Experts investigate the mysterious Creation of Man, asking whether unexplained advances in human evolution could have been down to aliens. (S3, ep 12)

Aliens And The Ancient Engineers: Experts investigate an ancient fortress in Peru said to have been built with laser tools. Could it prove that aliens once visited Earth? (S3, ep 6)

Sikorski's Last Flight: Explore the complex case of the death of Wladyslaw Sikorski, the Polish PM whose plane crashed soon after taking off in 1943. (S1, ep 2)

Hunting The Loch Ness Monster: New discoveries reveal the truth behind the Loch Ness Monster, and experts investigate evidence that a prehistoric monster could still be lurking.

Astronaut Encounters: To this day, NASA denies all UFO accounts and has taken measures to prevent its astronauts from telling their stories. But what are they hiding? (S3, ep 3)

Atmospheric Anomalies: Some experts believe many atmospheric light shows are actually caused by extraterrestrials. If so, do they pose an imminent threat to humanity? (S3, ep 4)

Alien Skies: From mid-air abductions to near-disasters caused by unseen enemies, experts examine if we are alone in the skies over Earth. (S3 ep 7)

The Next Wave: A fascinating look at the mounting evidence that suggests UFO waves are able to penetrate the world's most closely guarded airspace at will. (S3, ep 8)

Man vs Machine: When a Boeing 777 crashes into San Francisco Airport with no warning, engineers race to figure out what could have caused such a disaster. (6 of 6)

Drug Tunnels: A voyage through a world of historical adventure, exploring hidden rooms and underground labyrinths that were never meant to be seen by the public. (6 of 6)

Hidden In Plain Sight 1935-1938: In 1934, Hitler's government is firmly in the saddle. Most Germans support Hitler's anti-Jewish policy and the regime's terror soon escalates. (S1, ep 5)

The SS Death Head's Unit: Tasked with guarding concentration camps, this unit's actions knew no bounds, and, despite their heinous acts, still attended social gatherings. (S1, ep 5)

Cheetah Chase: An impala finds an unlikely escape from a cheetah, a skier is buried alive and a paraglider faces off with a kangaroo.

Everest Rumbles: The worst avalanche in recorded history wreaks havoc on the Everest base camp. A fisherman helps out a whale in the deep sea, and a clingy orangutan makes a friend.

Alien Origins: The compelling series returns to examine more eerie reports of UFOs. Can it determine where in the universe such strange flying crafts could be coming from? (S3, ep 1)

Astronaut Encounters: To this day, NASA denies all UFO accounts and has taken measures to prevent its astronauts from telling their stories. But what are they hiding? (S3, ep 3)

The Bitchy Inner Circle: Although it seemed like the biggest names in the Nazi Germany hierarchy were working together, behind the scenes nepotism, corruption and fear were rife. (5 of 6)

A Scottish Killing: Homicide detective Rod Demery and scientist Professor Turi King study an 800-year-old partial skeleton. Can they identify the killer? (S1, ep 4)

Normandy To The Rhine: The Western Allies of World War II launched the largest amphibious invasion in history when they assaulted Normandy, on 6 June 1944. (S1, ep 5)