Two hikers thought they had found a dead climber. Ten years later a radiologist noticed a flint arrowhead under the shoulder blade, and the oldest murder investigation in the world began.

A British airliner crossing the Andes signed off with seven letters nobody could read, then vanished for fifty-one years. The mountain eventually explained the crash. It has never explained the word.

A diver hunting hammerhead sharks off Japan's westernmost island found a wall of rock with right angles and steps. Forty years later, two credentialled geologists still cannot agree whether anyone built it.

German troops stripped it from a Russian palace in thirty-six hours and shipped it west. Eighty years later, six tonnes of carved amber remain missing, and nobody can even agree whether it still exists.

Between 1935 and 1938 a killer left dismembered bodies across Cleveland and Eliot Ness could not stop him. Nearly ninety years later, the county is exhuming the victims to give them back their names.

He had sent his bodyguards home. He and his wife walked out of a Stockholm cinema just after eleven at night and turned down a street full of people. What followed became the largest criminal investigation in Swedish history, and it ended in 2020 with a name and no trial.

She sailed from Texas with a cargo held liquid at 255 degrees and never arrived. A federal court ruled her owners liable for a loss nobody has ever been able to explain.

On a January morning in 1974, three teenagers came home from school and found their parents and their two youngest siblings dead in the house. For three decades the man who did it walked around their city as a church council president. He was caught because he could not stop writing to the police.

In sixteen days in 1998, someone cut a figure the size of a city into a South Australian plateau, then sent anonymous faxes about it. Nearly thirty years and a cash reward later, no one has claimed the work.

For four decades he was three different monsters with three different names, and the men hunting him could not agree that he was one person. The break, when it came, did not come from a witness or a confession. It came from strangers who had spat into a tube to find out where their grandparents were born.

Two Royal Navy ships sailed into the Arctic in 1845 and were never seen again. A single sheet of paper, found in a pile of stones fourteen years later, is still the only word any of the 129 men left behind.

Brickyard workers in Sichuan hit a pit full of giant bronze faces, elephant tusks and gold. Every object had been deliberately broken and burned first, and the people who made them never wrote a single word.