The TARDIS brings the new Doctor, Polly and Ben to the Earth colony planet Vulcan. The Doctor witnesses a murder and, investigating the body, discovers a pass badge allowing him unrestricted access to the colony.
A scientist, Lesterson, has meanwhile discovered a crashed space capsule containing inert Daleks, which he is now in the process of reactivating. The Doctor's warnings are ignored when the Daleks claim to be the colonists' servants.
COMMENT Spoliers ahead