A planet is discovered in the same orbit as Earth's but is located on the exact opposite side of the sun, making it not visible from Earth. The European Space Exploration Council decide to send American astronaut Glenn Ross and British scientist John Kane via spaceship to explore the other planet.
Unfortunately the movie Doppelgänger is not yet available on HBO Max.
| Directing | Robert Parrish | Director |
| Writing | Sylvia Anderson | Story |
| Production | Sylvia Anderson | Producer |
| Writing | Sylvia Anderson | Screenplay |
| Writing | Donald James | Screenplay |
| Editing | Len Walter | Editor |
| Production | Ernest Holding | Associate Producer |
| Camera | John Read | Director of Photography |
| Sound | Barry Gray | Original Music Composer |
| Art | Bob Bell | Art Direction |
| Production | Brian Burgess | Production Manager |
| Writing | Gerry Anderson | Story |
| Production | Gerry Anderson | Producer |
| Writing | Gerry Anderson | Screenplay |
| Visual Effects | Derek Meddings | Visual Effects Director |
| Costume & Make-Up | Barbara Ritchie | Hairstylist |
| Directing | Joan Davis | Continuity |
| Costume & Make-Up | Elsa Fennell | Wardrobe Supervisor |
| Directing | John O'Connor | Assistant Director |
| Sound | Ted Karnon | Sound Recordist |
| Production | Julie Leighton-White | Production Secretary |
| Art | Philip Bawcombe | Assistant Art Director |
| Costume & Make-Up | Gloria Barnes | Wardrobe Master |
| Costume & Make-Up | Geoffrey Rodway | Makeup Artist |
| Art | Chris Burke | Assistant Art Director |
| Sound | John Peverill | Sound Editor |
| Sound | Ken Rawkins | Sound Recordist |
| Production | Ivo Nightingale | Location Manager |
| Camera | Godfrey A. Godar | Camera Operator |
| Editing | Margaret Miller | Assistant Editor |
