What on Earth? Season 4

New evidence might reveal how the Mayans vanished; when scientists investigate an abandoned settlement, they discover traces of ritualistic drug binges from the ancient world; a mysterious symbol in the desert points to a sex cult of millionaires.

A ghost ship is found abandoned on a remote island that's home to one of the world's last uncontacted tribes. A strange labyrinth in Sicily might have a sinister connection to the Mafia. New evidence reveals a mysterious military compound in Russia.

Treasure hunters have searched for a lost Incan city of untold wealth for a century, but new technology might finally locate its riches; a strange mountain in Egypt sparks an investigation into Cleopatra's gems and the tomb of Alexander the Great.

New discoveries lead investigators to a crypt rumored to hold the Ark of the Covenant. When great white shark is killed, experts suspect an mysterious ocean monster. Strange markings in the desert might be a tribute to an ancient spider god.

A mysterious Stonehenge-like structure in Russia might have links to the Nazis. Experts uncover clues to a mega-tsunami with the power to devastate the United States. A huge lake appears in the Sahara overnight, and its explanation could be mythical.

Experts investigate a glowing lake reported to turn things into stone. A mysterious structure in Africa that resembles Stonehenge is said to be the resting place of a mythical giant. A dark conspiracy could be at work in the Australian outback.

An abandoned city in the African jungle might have a bloody past of malevolent spirits and cannibals. Mount Vesuvius shows signs that it's awakening, and the mafia could be to blame. Experts investigate Hitler's secret Nazi UFO program.

Man-made islands are spotted near a North Korean missile facility. When something unexpected is found in a remote desert, experts investigate a lost city of giants. A strange discovery in Siberia could reveal a mission to the center of the earth.

An ancient man-made volcano might reveal buried treasure and bloody human sacrifice. When NASA discovers a strange pattern in the Arctic ice, experts investigate if it has alien origins. A mystery in the Sahara might have a sinister explanation.

New evidence might finally identify the hiding place of the billion-dollar Nazi gold train; a discovery of a long-lost settlement rewrites the history of the Vikings in North America; a blood-red river in Siberia points to catastrophic pollution.

Evidence of human sacrifice for the Viking god Odin; shedding new light on Genghis Khan.

An abandoned megacity in a remote jungle might be the home of an ancient treasure and a dark secret; when a mysterious circular stone structure is discovered in Scotland, experts investigate whether it's the fabled Round Table of King Arthur.

A lost city near Jerusalem might have been the home of Goliath; bizarre underwater formations might point to a top-secret US weapons testing facility; a strange sighting in the Arctic could be a lost Nazi relic.

A strange lake in Transylvania is the home of an abandoned village and a terrifying secret. When an labyrinth is discovered on an island once home to an ancient Greek civilization, experts investigate if it was the legendary home of the Minotaur.

A forbidden island points to a strange South American town that locals claim was the home of Adolf Hitler. New data from NASA satellites might reveal a sunken lost continent in the Indian Ocean. A pit of bodies suggests fears of a zombie nightmare.

A strange forest of razor-shape stones could be home to an undiscovered Hobbit-like humanoid species; when a man-made island mysteriously appears off the US coast, new evidence points to secret government experiments into psycho-chemical warfare.

A ghost town covered in a strange, white power emerges from a lake in Argentina; upon the discovery of a lost jungle in Africa, scientists embark on a dangerous mission to explore it; a declassified CIA image uncovers a bizarre, giant Soviet weapon.

A ghost ship with links to the mob suddenly appears on a California beach; strange markings could be a coded message that reveals a plot to overthrow the Queen of England; a lake believed to have magical healing powers holds clues to life on Mars.

A strange structure shaped like a giant shark might point the way to a lost civilization's Fountain of Youth. A massive hurricane heads toward Florida but something unexpected is in its eye. Bizarre marks across the eastern US leave experts baffled.

Strange mounds in Transylvania might pinpoint the location of the tomb of the bloodthirsty tyrant believed to have inspired Dracula. A mysterious ancient city is discovered on a coral reef. Images of a plane crash sets off a hunt for a drug lord.