Well, endless war never works out. At least the Thals have always been friendly.
Wait, maybe not this time…
Yes, on one side we have the Kaleds holding the Doctor and Harry. They tried to escape, but the Kaleds recapture them. As it is, the Kaleds scan the pair and find the Doctor’s time ring. Since the Doctor is a prisoner, he can’t keep that. He also can’t get back to the TARDIS without it. That would be bad.
Also bad, Davros comes in with his new voice-powered Dalek. They attach a gun a to it. And then they set it loose. The Daleks are always some sort of critter with only one idea, so naturally, it was to kill Harry and the Doctor. Fortunately, by then, the military had turned them over to a scientist. And scientists (who aren’t any given story’s main villain) on Doctor Who are always at least a little helpful. So, he stops the execution because he still has tests to run. Davros doesn’t like that, but he accepts it.
And it turns out the scientist has reasons to worry. The military is working beyond what the scientists and the Kaled government want, with Davros genetically engineering stuff to put into mobile suits. You know, Daleks. Since the scientist who helped Harry and the Doctor is a helpful scientist, he helps some more by letting Harry and the Doctor escape through a vent.
But where’s Sarah Jane? People keep capturing her. First, it was the Mutos. Who are they? Well, that scientist said they’re the victims of all the chemical and biological weapons both sides were using during that thousand year war.
Yes, it’s a thousand year war.
But then the Thals show up and capture most of the Mutos. But wait, you say, aren’t the Thals good? Normally, yes. But not in this time. They’re building a weapon: a big missile with a lot of radioactive material with no shielding. So, basically, all the Kaled POWs and Mutos and such need to handle this stuff that kills them all quickly.
So, Sarah Jane arranges a jail break that seems to be working. You know, until they start climbing the rocket’s framework to escape and the Thals come in shooting. Many escapees are hit, and Sarah Jane falls off and…
Well, that’s where the episode ends, just before she goes splat.