In Search of... was a television series devoted to mysterious phenomena. It was created after the success of three one-hour TV documentaries produced by creator Alan Landsburg: In Search of Ancient Astronauts in 1973 (based on the book Chariots of the Gods?), In Search of Ancient Mysteries in 1974 and The Outer Space Connection in 1975. All three featured narration by Rod Serling, who was the initial choice to host the spin-off show. After Serling's death, Leonard Nimoy was selected to be the host.