In this replay episode: On a beautiful summer morning in 1908, a massive explosion hit Siberia. It downed 80 million trees and lit the night sky 3,000 miles away in Sweden. But to this day, no one knows what caused it.

The Backstory: Can Competition Destroy an Olympic Athlete?
09:05

The Backstory: The Night Wikipedia Almost Vanished
09:43

The Backstory: Nude Olympics
08:13