In a Mars base, the inhabitants are being infected by a mysterious water creature which takes over its victims. The Doctor is thrust into the middle of this catastrophe, knowing a larger one is waiting around the corner.
Acting
Tennant's volcanic 'Time Lord Victorious' transformation.
Direction
Harper's tight, suffocating base corridors amplify dread.
Writing
Russell T Davies scripts the Doctor's moral breaking point.
Director
Graeme Harper
David Tennant
The Doctor
Lindsay Duncan
Captain Adelaide Brooke
Peter O'Brien
Ed Gold
Sharon Duncan-Brewster
Maggie Cain
Gemma Chan
Mia Bennett
Aleksandar Mikic
Yuri Kerenski
Michael Goldsmith
Roman Groom
Cosima Shaw
Steffi Ehrlich
Joplin Sibtain
Tarak Ital
Alan Ruscoe
Andy Stone
Max Bollinger
Mikhail
Charles De'Ath
Adelaide's Father
Trivia, insights & behind the scenes
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