'Trial by Robot' by Alan Fennell

When important robots vanish from several planets, Matt suggests questioning Professor Himber, a famous robot scientist whose recent tour took him to the same planets as the kidnappings. Steve and Venus become concerned that Robert could be the next victim, and they place an alarm on their mechanical pal. When the deranged Himber tries to snatch Robert he finds the device; realising he is being watched, Himber leaves Earth, having programmed Robert to steal a spaceship and follow his new master. The Fireball XL5 crew set off on in pursuit – but when they arrive on Planet 82 they are captured by Himber and his robot servants and put on trial for their lives...

Paul Maxwell (Colonel Steve Zodiac), Sylvia Anderson (Doctor Venus), David Graham (Professor Matt Matic / Lieutenant 90 / Professor Al Himber), John Bluthal (Commander Zero), Gerry Anderson (Judge Robot / Prosecutor Robot / Jury Robot 1 / Jury Robot 2 / Jury Robot 3)

Directed by Bill Harris
Produced by Gerry Anderson
Associate Producer Reg Hill

TX (UK - ITV):
7th October 1963

Notes:
*Featuring Colonel Steve Zodiac, Venus, Professor Matt Matic, Commander Zero and Lieutenant 90