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.
as The Doctor
as Captain Adelaide Brooke
as Ed Gold
as Maggie Cain
as Mia Bennett
as Yuri Kerenski
as Roman Groom
as Steffi Ehrlich
as Tarak Ital
as Andy Stone
as Emily
as Mikhail
as Adelaide's Father
as Young Adelaide
as Ulrika Ehrlich
as Lisette Ehrlich
as Ood Sigma
