Dr. Russell's long-lost husband, Lee, appears on an Eagle returning from an Earth-like planet. He warns that the planet is not for them and that a power greater than they can understand will destroy them if they go there. Koenig must decide whether to listen to Lee's warning or evacuate the Moon before it's too late.
Elenco: Martin Landau , Barbara Bain , Catherine Schell , Barry Morse , Tony Anholt , Nick Tate , Prentis Hancock , Zienia Merton , Clifton Jones , Anton Phillips .