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 |
| Writing | Sylvia Anderson | Screenplay |
| Production | Sylvia Anderson | Producer |
| Writing | Donald James | Screenplay |
| Camera | John Read | Director of Photography |
| Production | Ernest Holding | Associate Producer |
| Production | Brian Burgess | Production Manager |
| Editing | Len Walter | Editor |
| Art | Bob Bell | Art Direction |
| Sound | Barry Gray | Original Music Composer |
| Writing | Gerry Anderson | Screenplay |
| Writing | Gerry Anderson | Story |
| Production | Gerry Anderson | Producer |
| Visual Effects | Derek Meddings | Visual Effects Director |
| Costume & Make-Up | Barbara Ritchie | Hairstylist |
| Costume & Make-Up | Geoffrey Rodway | Makeup Artist |
| Directing | John O'Connor | Assistant Director |
| Art | Philip Bawcombe | Assistant Art Director |
| Art | Chris Burke | Assistant Art Director |
| Sound | Ted Karnon | Sound Recordist |
| Sound | John Peverill | Sound Editor |
| Sound | Ken Rawkins | Sound Recordist |
| Costume & Make-Up | Gloria Barnes | Wardrobe Master |
| Costume & Make-Up | Elsa Fennell | Wardrobe Supervisor |
| Camera | Godfrey A. Godar | Camera Operator |
| Editing | Margaret Miller | Assistant Editor |
| Production | Ivo Nightingale | Location Manager |
| Directing | Joan Davis | Continuity |
| Production | Julie Leighton-White | Production Secretary |
