Captain Caveman & the Teen Angels

A girl asks the Teen Angels to guard a key with their lives. They follow her to an old mansion where a group of beneficiaries is about to discover the secret of their keys from the Great Mysto. When the lights go out Mysto and the keys disappear. The Teen Angels rescue Mysto and discover the keys lead to a treasure. Chuck, Sandy and Sue's plane is forced down on Mystery Island by diabolical Dr. Strange, who needs their robot, POPS, to complete his plan for world domination. After a frightening encounter with the mysterious Mud People, POPS, activates his force field to protect the group from Kreeg and his henchmen--but not in time to save Chuck from Dr. Strange's Gravity Ray. At a beach party, the Teen Angels watch a huge ship beneath the lighthouse light disappear at Dead Man's reef. While investigating the disappearance, DeeDee is locked in a cave by a masked man. There she finds lenses, pictures of a ship and a secret entrance to the lighthouse. She learns the ship's owner made a hologram of the ship, lit it with the lighthouse beam, then tried to collect the $3 million insurance with the claim that the ship sank.