The last episode left Ian being dragged to the edge of an abyss. The Thal who slipped and is hanging at the other end of the rope, cuts it and sacrifices himself for the good of the tribe and their ultimate goal.
The group seem to be wandering through the set aimlessly, until a small hole is discovered and the find the way into the city.
Viewers are taken back to where the Doctor and Susan are being held captive by he Daleks. Its revealed that the Daleks now intend on setting off all the nuclear reactors instead of a bomb. In their tiny voices they gleefully inform the Doctor that they have the power to survive the impact where as all other life will be wiped out.
The Doctor tries to negotiate with them, telling them that he can build them a TARDIS so that they can travel off the planet.
All groups of the Thals meet up and begin an attack on the Dalek control centre. Ina flurry of activity, they are able to destroy the machinery and disable the power sources the Daleks have for the city.
The Daleks loose their mobility and beg the Doctor to repair their systems and save them. He refuses to help them and collects his small group of time travellers, along with their fluid link and returns to the tribes camp.
A tearful farewell sees Barbara kiss one of the tribe members before rushing into the TARDIS.
As son as they have set course, the console of the TARDIS explodes and the team are thrown to the floor.