A signal sent out by Will is locked onto by a spaceship, and the Robinsons warily watch as the radar signal shows the ship approaching, then land. Don, John, Smith, Will and the Robot go out to check on what landed, and they find astronaut Jimmy Hapgood, also lost from Earth after he missed a landing on Saturn many years earlier. They help him repair his ship, Traveling Man, which is in better condition than the Jupiter 2, so that he can return to Earth. Smith removes a navigational device from the Robot that Hapgood can use.