SHADO engages in its first battle with the enemy. Sky One cripples an alien ship which crash-lands in a lake. Straker's team capture its pilot, a strange blue-skinned humanoid - and the grim secret behind the aliens' are revealed.
| Name | Type | Role | |
|---|---|---|---|
| Reg Hill | Writer | ||
| Tony Barwick | Writer | ||
| Gerry Anderson | Writer | ||
| Sylvia Anderson | Writer | ||
| Gerry Anderson | Director | ||
| Annette Kerr | Actor | Nurse | |
| Jon Kelly | Actor | Skydiver Engineer | |
| Basil Dignam | Actor | Cabinet Minister | |
| Wanda Ventham | Actor | Virginia Lake | |
| Gary Myers | Actor | Lew Waterman | |
| Georgina Moon | Actor | Skydiver Operative | |
| George Sewell | Actor | Col. Freeman | |
| Gary Files | Actor | Phil Wade | |
| Michael Mundell | Actor | Ken Mathews | |
| Peter Gordeno | Actor | Capt. Carlin | |
| Dolores Mantez | Actor | Nina Barry | |
| Shane Rimmer | Actor | Seagull X-Ray Co-Pilot | |
| Matthew Roberton | Actor | Dr. Harris | |
| Harry Baird | Actor | Mark Bradley | |
| Ed Bishop | Actor | Cmdr. Straker | |
| Jeremy Wilkin | Actor | Skydiver Navigator | |
| Gabrielle Drake | Actor | Lt. Ellis | |
| Maxwell Shaw | Actor | Dr. Shroeder | |
| Keith Alexander | Actor | Shado Radio Operator | |
| Grant Taylor | Actor | General Henderson | |
| Paul Gillard | Actor | Kurt Mahler | |
| Antonia Ellis | Actor | Joan Harrington |