Back in their underground city, the Daleks have duplicated the sample of Thal anti-radiation medicine they took from Susan a couple of episodes ago, and are testing it on a small number of their own. Monitoring the escaped prisoners in the radioactive forest, they have also observed that the Doctor and his companions have met up with the Thals. After their ambush on the Thals who came to the city for peace negotiations, they expect a retaliatory attack.
Not that the Daleks are wrong about the anticipated attack, but it’s not the Thals who are making battle plans.
The Doctor’s group need the help of the Thals to retrieve the fluid link, a little piece of machinery that makes the Tardis run, and which Ian had taken away from him when the Daleks captured him. They must go back into the Dalek city for it, but they need reinforcements. The Doctor is certain that the Thals “will triumph, with me to lead us,” and doesn’t see why he shouldn’t use them for his own ends. Barbara agrees that they need the Thals to fight to aid them in leaving this planet. Ian, on the other hand, is against asking these people to sacrifice their lives for a little gizmo that means nothing to them. There’s much debate on the subject.
The Thals have become firm pacifists since they wiped out nearly all life on Skaro with their neutron-bomb war 500 years ago, so they’re going to be tough to convince to go back to their old warrior ways.