T. Galaxy Four
The TARDIS materialises on an arid planet where they encounter two stranded races - the Drahvins and the Rills who, due to an encounter in space, both crashed onto the planet's surface. The Rill ship is almost ready for take off having been repaired by robotic drones affectionately nicknamed Chumblies by Vicki. The Drahvin ship is irreparable.
The Rills appear to be a peaceful and welcoming explorers whilst the Drahvins appear as mindless clones lead by the warlike Maaga. The Doctor discovers that the planet is soon to self destruct, and both species are in a rush to get off the planet.
The Drahvins plan to force the Doctor to help them steal the Rills' spacecraft to escape. Instead the Doctor povides the Rills with power from the TARDIS which refuels their ship and allows the Rills to escape, leaving the Drahvins to their fate.
- Vicki: Maureen O'Brien
- Steven Taylor: Peter Purves
- Maaga: Stephanie Bidmead
- Drahvin One: Marina Martin
- Drahvin Two: Susanna Carol
- Drahvin Three: Lyn Ashley
- Chumbley Operators: Jimmy Kaye (1), Angelo Muscat, Pepi Poupee (3-4), Tommy Reynolds (4), William Shearer
- Rill Voices: Robert Cartland (3-4)
- Jeff Garvey: Barry Jackson (4)
- Rills: (all 3-4) David Brewster, Peter Holmes, Brian Madge, Bill McAllister
|BBC 1||82. Four Hundred Dawns||Saturday, September 11, 1965 5:40 PM - 6:05 PM||9.0M||56%|
|BBC 1||83. Trap Of Steel||Saturday, September 18, 1965 5:50 PM - 6:15 PM||9.5M||55%|
|BBC 1||84. Air Lock||Saturday, September 25, 1965 5:50 PM - 6:15 PM||11.5M||54%|
|BBC 1||85. The Exploding Planet||Saturday, October 2, 1965 5:50 PM - 6:15 PM||9.9M||53%|
- Ealing Television Film Studios
- Television Centre Studio 3
- Television Centre Studio 4
Episode 4 : Garvey, who is credited for part four of this story by the Radio Times is a character from Mission to the Unknown, who appears as part of a cliff-hanger lead-in to this next episode.