Lost in Space - Season 2 - Eps 12: A Visit to Hades
Dr Smith, Will and the Robot discover an old harp under a carved out rock. They discover that in playing the right tune, it unlocks a passage to another world. In travelling here, Dr Smith meets an alien who believes to be the devil, and believes the place to be Hell. When he leaves, and the Alien shows up on the planet, Dr Smith is frightened. Judy befriends the alien, and is accidently taken to the other world. It is up to Don and John to save her, and finally Dr Smith realises it is not hell, and merely a prison world for a criminal.
About Lost in Space

Title: Lost in Space
First Air Date: 1965-09-15
Last Air Date: 1968-03-06
Status: Ended
Rating: 7.1/10 (from 115 votes)
Language: EN
Seasons: 4
Total Episodes: 83
Network: CBS
Genres: Sci-Fi & Fantasy, Comedy
Production Companies: Irwin Allen Productions, 20th Century Fox Television
Synopsis
The space family Robinson is sent on a five-year mission to find a new planet to colonise. The voyage is sabotaged time and again by an inept stowaway, Dr. Zachary Smith. The family's spaceship, Jupiter II, also carries a friendly robot who endures an endless stream of abuse from Dr. Smith, but is a trusted companion of young Will Robinson
Cast

Guy Williams
Dr. John Robinson

June Lockhart
Dr. Maureen Robinson

Mark Goddard
Major Don West

Marta Kristen
Judy Robinson

Angela Cartwright
Penny Robinson

Bill Mumy
Will Robinson

Jonathan Harris
Dr. Zachary Smith

Dick Tufeld
Robot B-9

Bob May
Robot B-9