Sometimes the creepiest thing is a gaping unknown. Whether it’s a disappearance or a mysterious death, there are plenty of books about unsolved events to keep you awake at night.

Dead Mountain
Donnie Eichar

In 1959, a group of nine experienced climbers took a trek into the Ural Mountains. They never returned. The rescue crews found their remains and their campsite but it didn’t make sense. Why would hikers have left their tent, without shoes or coats? Why would they have cut their way out of the tent at all? Why would they have run away in different directions, to certain death in the cold, inhospitable wilderness? The book has a compelling answer, though it is by no means conclusive. More.

Arthur & George
Julian Barnes

A novel based on true events, it recounts the wrongful conviction and imprisonment of George Adaji. His case was known to Sir Arthur Conan Doyle, who helped to get the man released. The actual perpetrator of the crimes is still unknown. I also recommend Conan Doyle for the Defense by Margalit Fox, which outlines the second real-life case that Conan Doyle worked on. More.

The Suspicions of Mr. Whicher
Kate Summerscale

In this nonfiction book, Summerscale brings together the facts of the case along with the societal changes that made it a sensation. Higher literacy rates and newspapers, together with train travel, made the story travel quickly. The infancy of British policing and the inimitable Mr Whicher, who inspired the modern detective novel. The Road Hill murder is technically still unsolved. More.

Meet Me In Atlantis
Mark Adams

Adams presents the various theories and cases for Atlantis in this self-deprecating book. Part travelogue, part memoir, part history lesson, he shares both his childlike zeal and his scientific findings. Even if Atlantis isn’t real, he tries to find clues as to what might have inspired the stories. My review

The Midnight Assassin
Skip Hollandsworth

Historians argue over the “first” serial killer in America, but this one, that terrorized Austin, Texas, is a good candidate. Hollandsworth pulls together dozens of first-hand accounts, newspaper clippings, police reports and more to create a portrait of the crime spree. The true identity is still unknown. My review

Monsters Among Us
Linda S. Godfrey

Godfrey approaches the subject of bigfoot, werewolf, and other strange sightings scientifically. She takes measurements, detailed statements, and looks for other evidence. Then she compiles it and looks for commonalities. While it seems Godfrey is herself a believer in the otherworldly, she writes clearly and succinctly on the cases she investigates. More.

What unsolved mystery keeps you up at night?