Is it possible that Earth was visited by extra-terrestrials thousands of years ago? If so, was evidence left behind? ANCIENT ALIENS: SEASON 3 continues HISTORY’s gripping exploration of Ancient Astronaut Theory. Whether investigating the possible extra-terrestrial origins of zombies and vampires, or probing the otherworldly mysteries of Earth’s deadliest places, each episode delves into the historic facts and surprising evidence that suggests an answer to the ultimate question: Have alien beings influenced human history on Earth?