Lost in Space - Season 3 - Eps 18: Time Merchant
Will is conducting an experiment in a cave and captures a man who claims to be the man who controls time for the entire universe. This ""Time Merchant"" takes Will, Professor Robinson, Smith, and the Robot, to his secret lair. From there, Smith uses the Time Merchant's time machine to return himself to Earth on the day the Robinson's departed, with the objective of NOT sabotaging the Jupiter II mission and letting the Robinsons go on their way to Alpha Centauri. The Time Merchant then announces that if Smith does not get on the Jupiter II, the ship will not fly off course and will therefore be destroyed by a collision with an asteroid several months after liftoff. So Will is sent back to join Smith and try to convince him to get on the Jupiter II as he originally did.
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