The planet Skaro, the distant past. The Time Lords divert the Doctor, Sarah Jane and Harry to this war-torn world, and give the Doctor a mission: the evil of the Daleks is about to be born here, and the Doctor is to try to ensure they evolve into less lethally aggressive beings - or, failing that, to avert their creation altogether. But has even the Doctor the right to commit genocide?

The Doctor and Harry are taken to the Kaled bunker where Davros is preparing to demonstrate the Daleks, while Sarah Jane is captured by the Thals and taken to their city as a slave worker.

The Doctor fails to prevent the Thals from destroying the Kaled city but they don't have long to enjoy their victory before the Daleks attack.

The Doctor is forced to give Davros full details of future Dalek victories but opposition to Davros' plans is growing among the Kaleds and soon there is open rebellion.

Gharman tries to convince the Kaleds to vote against the Dalek project but Davros has a trick up his sleeve, while the Doctor works to destroy the tape recording of Dalek victory and the Thals plan an intervention of their own.