Scholars reexamine the witch trials in 17th-century Salem, Mass., uncovering fresh clues about the town's dark past; experts use 3D computer mapping techniques and ground-penetrating radar to rediscover the long-lost site of the witch hangings.

Experts surmise that a plot to assassinate Confederate President Jefferson Davis in the so-called Dahlgren Affair may have changed the course of the American Civil War and been the driving force behind the assassination of President Lincoln.

The flu pandemic of 1918 is the hidden apocalypse of the 20th century, killing as many as 50 million people around the world; with new evidence, scientists investigate the truth behind the so-called Spanish flu to see if it could happen again.

Newly declassified intelligence documents paint a new picture of the attack on Pearl Harbor, including information regarding a spy ring that funneled American intelligence and stolen technology to the Japanese Navy, making the attack possible.

In 1982, satellites detect a massive explosion in the Siberian wilderness; new evidence reveals this may have been a CIA operation, utilizing the newly emerging field of computer viruses to get revenge on the Soviet Union for decades of espionage.

When forensic anthropologists disinter the body of American Revolutionary war hero Gen. Casimir Pulaski, they find the skeleton of a woman; researchers wonder if the commander was a woman and whether this explains the general's strange behavior.