The Phantom Planet is a 1961 science fiction film directed by William Marshall. Since spaceships keep disappearing in the asteroid belt between Mars and Jupiter, astronaut Captain Frank Chapman (Dean Fredericks) flies there on a mission to discover what has happened to them. While he is exploring the region, his ship is hit by a meteor shower and lands on an asteroid. He then discovers that the asteroid, named Rheton, is inhabited by tiny people led by Sesom (Francis X. Bushman). Due to the odd atmospheric conditions on Rheton, Captain Chapman shrinks to their six-inch size as well. Soon, he finds himself in a love triangle with two beautiful Rhetons, the princess Liara (Coleen Gray) and a mute woman named Zetha (Dolores Faith). He also begins a rivalry with Herron (Anthony Dexter), Liara's boyfriend, and tries to save the Rhetons from the evil Solarites, monsters that are trying to take over the asteroid.