After NASA's New Horizons spacecraft flies by Pluto, it encounters a strange alien world that shuts down the probe's computers, and experts investigate if this mysterious object is an alien spacecraft hiding at the edge of our solar system.
When astronomers discover a rogue black hole speeding through the Milky Way, they investigate how much danger this cosmic monster poses to Earth, and what would happen if it ever entered our solar system.
When a former Area 51 insider alleges that the Roswell UFO incident was a nefarious Soviet conspiracy masterminded by Stalin, experts investigate if it was indeed an enemy plot against America -- or if the confession is just another cover-up.
After Neil Armstrong's moonwalk, he led an expedition into the Amazon to find a legendary library that holds all knowledge of an advanced alien civilization. Experts ask if a close encounter on the moon's surface inspired Armstrong's mysterious quest.