1. Area 51

Hidden in the Nevada desert, a top-secret military base remains one of the most heavily restricted sites in the United States; since the 1950s, speculation has swirled about its true purpose-ranging from hiding experimental aircraft and even alien technology; Area 51 keeps its mysteries so closely guarded that not even the president is fully briefed; what is the government really hiding there?

2. The Hunt for Adolf Eichmann: Case Closed

At the end of World War II, many Nazi officials were captured and tried for their crimes. But one of the architects of the Holocaust, Adolf Eichmann, slipped through the cracks…repeatedly eluding Nazi hunters from around the globe.

4. The Theft of the Mona Lisa: Case Closed

The world's most famous painting vanishes in a daring heist, sparking international outrage and a global manhunt. A master detective is called in, who zeroes in on a handful of suspects with the motive and means to pull off the theft. Who stole the legendary Mona Lisa?

5. The Hunt for the Kraken

It’s one of the most legendary monsters said to be lurking in the vast open seas. With stories going back hundreds of years, this elusive creature has terrorized sailors and baffled scientists.

6. The Murder of Sam Giancana

The notorious mafia kingpin, Sam Giancana, is shot execution style in his own home. The larger-than-life mobster had many enemies, from inside the mafia to the CIA.

7. The Unabomber: Case Closed

A twisted mastermind uses homemade bombs to terrorize the nation. Despite one of the most extensive manhunts in U.S. history, he still manages to stay one step ahead of law enforcement for nearly two decades.

8. Who Is the Boston Strangler?

A series of shocking murders shake the city of Boston to its core. Each victim, 13 women in all, bore the signature of this serial killer.

9. The Plot to Kill Lincoln

A shot rings out from the balcony of the Ford's Theater in Washington, D.C. and America's 16th president has been killed. Who was behind the plan to assassinate President Lincoln?

10. The Hunt for El Chapo: Case Closed

El Chapo is an untouchable drug lord who sat atop a criminal empire and became the most wanted man in the world. How did investigators finally bring El Chapo to justice?

11. What Killed Bruce Lee?

Bruce Lee was a seemingly invincible icon and the closest thing that we had to a real-life superhero. What killed him?

12. The Hunt for Viking Treasure

Known for their seafaring skills and feared for their ferocity, the Vikings amassed gold, silver and other riches while trading and raiding across Europe; catches of this treasure have been found in Europe and North America, but this may be just the tip of the iceberg; are there any rich Viking hoards still waiting to be found? And if so, where are they?

13. The Lufthansa Heist

On December 11, 1978, a gang of thieves lift around $5 million in cash and $800,000 in jewelry from a luxury airline hangar at New York's JFK Airport, marking the largest heist in U.S. history at that time.

14. Foo Fighters: WWII Edition

During World War II, a fiery phenomenon terrorizes American airmen in the night skies over Europe. The pilots call these fireballs "Foo Fighters," and swear they move at over 200 mph and defy the laws of physics. But what are they?

15. Rommel's Gold: WWII Edition

General Erwin Rommel captured territory, imprisoned local Jews in camps, and stole their gold and valuables in the name of the Führer. For decades, many have looked for this elusive treasure. What became of Rommel's gold?