The screenplay by Irving Block and Allen Adler, written in 1952, was originally titled "Fatal Planet". The later screenplay draft by Cyril Hume renamed the film "Forbidden Planet", because this was believed to have greater box-office appeal. Block and Adler's drama took place in the year 1976 on the planet Mercury. An Earth expedition headed by John Grant is sent to the planet to retrieve Dr. Adams and his daughter Dorianne, who have been stranded there for twenty years. From then on, its plot is roughly the same as that of the completed film, though Grant is able to rescue both Adams and his daughter and escape the invisible monster stalking them.