A NASA spacecraft proves Einstein right when, traveling faster than light, it ends up near King Arthur's Camelot. On board are big-hearted Tom Trimble and Hermes, the look-alike robot he built. Tom immediately makes friends with pretty Alisande while becoming enemies with the evil knight Sir Mordred. It seems Mordred has joined up with the Sorcerer Merlin and they are both up to no good. It is now up to Tom to try and use 20th century technology to foil their plans.
| Actor | Role |
|---|---|
 Jim DaleSir Mordred | Sir Mordred |
 Kenneth MoreKing Arthur | King Arthur |
 Ron MoodyMerlin | Merlin |
 John Le MesurierSir Gawain | Sir Gawain |
 Rodney BewesClarence | Clarence |
 Dennis DuganTom Trimble | Tom Trimble |
 Pat RoachOaf | Oaf |
 Sheila WhiteAlisande | Alisande |
 Robert BeattySenator Milburn | Senator Milburn |
 Cyril ShapsDr. Zimmerman | Dr. Zimmerman |
| KKevin BrennanWinston | Winston |
 Ewen SolonWatkins | Watkins |
 Reg LyePrisoner | Prisoner |
 Bruce BoaAir Force Officer (Uncredited) | Air Force Officer (Uncredited) |
 Al LampertNASA Technician (Uncredited) | NASA Technician (Uncredited) |
| DDerek SuthernNASA VIP (Uncredited) | NASA VIP (Uncredited) |