In February 1978, five friends left a college basketball game in California and were found months later, 110 kilometres off course on a frozen mountain. One of the Yuba County 5 had survived for weeks inside a shelter stocked with food he never touched, and a sixth question has haunted the case ever since: what became of Gary Mathias?

In 1908, a clay disc stamped with 241 mysterious signs emerged from a Minoan palace on Crete. It may be the world's first printed text — and no one can read it.

Easter Island's wooden tablets carry one of the last undeciphered scripts on Earth — and a 2024 dating study hints it may have been invented with no outside help at all.

In November 1955 the MV Joyita was found half-submerged and drifting in the South Pacific, five weeks overdue, her radio tuned to the distress frequency and a doctor's bag of bloodstained bandages on deck. Her cork-lined hull made her almost unsinkable. So why did all 25 aboard abandon her — and where did they go?

In March 1918 the USS Cyclops, a massive US Navy collier, sailed from Barbados toward Baltimore and dissolved into the Atlantic. No SOS, no wreckage, no bodies — the Navy's greatest non-combat loss remains unexplained, and the ship has never been found.

A century ago an epidemic put its victims to sleep, then locked the survivors inside frozen bodies for years. Doctors never found what caused it.

In 1994, nurses and doctors at a California hospital collapsed one after another while treating a dying woman. Three decades later, science still cannot fully explain what happened that night.

Millions of barren circles freckle the Namib grasslands in an eerily regular pattern. After decades of study, scientists still cannot agree on what makes them.

On a June night in 1912, an entire household in a small Iowa town was killed while sleeping. More than a century, two trials and countless theories later, no one has ever been convicted.

An 1885 pamphlet claimed a fortune in gold lies buried in Virginia, its location locked in unsolved ciphers. Skeptics say the treasure never existed - yet people are still digging.

For decades, silent balls of light have floated over a remote Norwegian valley — and for over forty years, scientists with cameras, radar and magnetometers have been trying to explain them. They still can't.

In 1897, Edward Elgar slipped a young friend a card covered in 87 curling symbols. She never managed to read it, no one has since — and the man who wrote it took the answer to his grave.