Some stories never get an ending. Not because investigators stopped trying, but because the answers simply never came. These seven cases have stumped experts for decades, and in some cases, for centuries. Each one is a genuine puzzle that remains unsolved to this day.
A Plane With 239 People Aboard Just Vanished
On March 8, 2014, Malaysian Airlines Flight 370 left Malaysia headed for China with 239 passengers on board. Less than an hour after takeoff, the plane veered off its planned route and its transponder went dark.
Radar tracked it over the Indian Ocean for nearly eight more hours. Then it disappeared completely.
What followed was the largest multinational search effort in the history of aviation. It turned up almost nothing. Over the past 12 years, only three pieces of debris confirmed to be from the plane have ever been found. The plane itself, and everyone on board, has never been located.
Some believe a meteor struck the aircraft. Others point to the fact that the captain had flown a nearly identical route on his home flight simulator about a month before the flight. No one knows the truth.
A Mother Who Knew Her Own Son
In 1928, Christine Collins, a single mother in Los Angeles, reported that her 9-year-old son Walter was missing. Five months passed. Then police arrived at her door with a boy they believed to be Walter.
Christine told them clearly and firmly: this was not her son. The police did not believe her. They went so far as to have her committed to a mental institution for saying so.
The real Walter Collins was never found. Authorities suspected he was killed by Gordon Stewart Northcott, a convicted child murderer who was executed in 1930. But the evidence was never conclusive. The case was so disturbing that Clint Eastwood turned it into a film, Changeling, in 2008. Nearly a century later, no one knows what happened to Walter, or why police were so determined to force a stranger on his mother.
A Ship Found Perfectly Intact With No One on It
In November 1872, a ship called the Mary Celeste left New York bound for Genoa, Italy. On board were Captain Benjamin Briggs, his wife, their 2-year-old child, and seven crew members. The ship carried practical supplies as well as some finer things, including a piano and a sewing machine.
Captain Briggs kept a detailed written log of the voyage. His final entry reported nothing unusual.
On December 4, less than two months after departing, another vessel came across the Mary Celeste floating at sea. The ship was in perfect condition. Everything was in its place. The only thing missing was every single person who had been on board. They were never found.
Pirates seemed unlikely because nothing had been stolen or damaged. Decades later, scientists suggested that alcohol stored in the cargo hold may have released fumes that panicked the crew into abandoning ship. But that theory never fully explained what happened to them afterward.
Two Little Girls Who Seemed to Know Things They Couldn’t
In 1957, two sisters named Joanna, age 11, and Jacqueline, age 6, died in a car accident in England. A year later, their mother gave birth to twin girls, Gillian and Jennifer.
As the twins grew old enough to walk and talk, something unsettling began to happen. They asked for specific toys that had belonged to their deceased older sisters, toys they had never seen. They recognized the school that Joanna and Jacqueline had attended, even though they had never been told about it. And they were gripped by an intense, unexplained fear of moving vehicles.
As the girls got older, all of it stopped. They went on to live completely ordinary lives. But psychiatrist Ian Stevenson, who spent his career studying reincarnation, investigated the case and chose to include the Pollock sisters in his book on 14 cases of reincarnation that he believed to be credible.
A 600-Year-Old Book Written in a Language No One Can Read
Picture finding an old book with no author, no date, and no title. It’s written in a language that no scholar, linguist, or codebreaker has ever been able to identify. That is exactly what alchemist Georg Baresch encountered sometime between 1585 and 1692, when he discovered an unusual manuscript among his possessions.
The book passed from owner to owner for centuries. In 1912, it reached a Polish book dealer named Voynich, and it has carried his name ever since. Carbon dating placed its origins in the 1400s. At 250 pages, it appears to be a medical text of some kind. Voynich guessed it was written by either alchemist Albertus Magnus or scientist Roger Bacon, but that was never confirmed.
More than 600 years after an unknown person set pen to parchment, no one has ever cracked the Voynich Manuscript. Its language, its purpose, and its author remain a complete mystery.
Nine Hikers Who Never Came Home
In February 1959, nine hikers set out into the Ural Mountains of Russia to cross a high mountain pass called Dyatlov Pass. They pitched their tent, ate a meal, and went to sleep. Twenty-five days later, when none of them had returned, authorities went looking.
What they found was deeply disturbing. The tent had been ripped open and abandoned. Footprints in the snow — some barefoot, some in socks, some with a single shoe — led investigators deeper into the woods. The first two bodies were found wearing almost nothing, despite the brutal cold.
The remaining seven were found in worse condition. One had been burned. One showed signs of blunt force trauma. Another was missing a tongue. And their clothing tested positive for radioactivity.
Theories have ranged from a Yeti encounter to alien activity to a drug overdose. A documentary filmmaker proposed that “infrasound”, a low hum created when wind moves across certain terrain, may have triggered extreme panic, nausea, and dread. The cause of all nine deaths was officially listed as undetermined, and it remains that way today.
A Mysterious Illness That Turned People Into Living Statues
Between 1917 and 1928, a condition called encephalitis lethargica, sometimes called “sleeping sickness”, swept through Europe and then spread to India and North America. It infected more than half a million people.
Those who fell ill were fully conscious. Their minds worked. But they could not move their bodies. They were aware of everything around them, essentially frozen in place. Some could briefly speak or move their eyes. Others remained in that state for days, weeks, or even years. About one third of those infected did not survive. Those who did often remained physically unable to move for extended periods.
The illness appeared to fade away, then surfaced again in Europe in the 1950s. In 2010, it appeared once more in China, where a child was hospitalized for five weeks.
Researchers who studied patients with similar symptoms in 2004 concluded that whatever causes encephalitis lethargica is likely still out there. Brain inflammation is suspected, but the exact cause has never been identified. After more than a century of study, this one remains as baffling as ever.