The TARDIS arrives on the Earth colony of Vulcan where the newly-regenerated Doctor assumes the identity of an Earth Examiner.

While the Doctor worries about the inert Daleks in the capsules, Lesterson makes plan to reactivate one of them.

The Doctor fails to convince the colonists of the danger posed by the Daleks and soon the other two are also reactivated.

With Polly being held prisoner by the rebels, the Doctor and Ben decide to investigate them, while Lesterson discovers the Daleks are reproducing.

The Doctor and Quinn attempt to escape in order to stop Bragen using the Daleks to take over the colony.

With Bragen having taken over, the Daleks trick the rebels into turning them loose and only the Doctor can stop them wiping out the entire colony.