The Expedition opens with Ian ranged against the Doctor and Barbara.  The fluid link needs to be retrieved from the Dalek City, but Ian is reluctant to ask the Thals to help them (“What victory are you going to show these people when most of them have been killed? A fluid link? Is this what you’re going to hold up to them and say, ‘Thank you very much. This is what you fought and died for’?”).

The Doctor has no qualms in asking for the Thals’ help – he needs the fluid link back and they’re a ready made fighting-force, so it’s of no concern to him whether they all die in the attempt.  Barbara is equally keen to retrieve the fluid link and escape from Skaro – she’s convinced that the Daleks will find a way to travel out of the city and kill them all (“Oh, they’ll find a way. They’re clever enough. They’ll find us and kill us, you know that as well as I do.”)

There’s no evidence to support this though (is she simply playing on Ian’s fears for their safety?) and he remains resolute.  It’s a key part of the story and it’s a little surprising to find this debate in a Terry Nation story – his yarns tended to be drawn in more clearly defined shades of black white.  In the end Ian does persuade the Thals to help – by making them see that they will also be guaranteeing their own survival.  At one point Barbara complains that Ian is only playing with words and there’s more than a kernel of truth in this.

In the Dalek City there’s some interesting things going on, thanks to Christopher Barry’s direction.  A group of Daleks have elected to take the Thals anti-radiation drugs (inducing death).  We see one of the Daleks die from their POV, in a slightly trippy, drug-induced way.  The moans emanating from the Dalek do sound slightly comic, but it’s another reminder that in this story they’re not portrayed just as mindless killing machines.  These signs of vulnerability, together with their more conversational mode of speech, would later be dropped as the Daleks lose any spark of individuality (except maybe for David Whitaker’s two Troughton stories).

It does feel a little contrived that the Daleks only now realise the anti-radiation drugs don’t  work since they’ve become conditioned to radiation and need more of it to survive.  Therefore they intend to release another bomb which will also have the pleasing side effect of wiping out of Thals.  The war ended five hundred years ago, why have the Daleks only just twigged that radiation is essential to their survival?

The Doctor elects to mount a two-pronged attack – one group to distract the Daleks on the city wall whilst the others attempt to break into the city from the rear – braving the jungle and the lake of mutations.  This is the first of Terry Nation’s Doctor Who jungles and despite it’s small size is effectively realised.  Partly this is due to Brian Hodgson’s sound design which creates a real sense of unease (Ian beating off a clip of stock footage is less impressive).

The monster that rises out of the swamp is another decent moment, although it does slightly look like a rubber ring with two glowing eyes.  As previously mentioned, on the lower resolution televisions of the time this no doubt would have looked more convincing.  Although I’m quite convinced now – maybe I’m easily pleased?

Ian and Barbara are accompanied by five Thals – although their party is quickly reduced by one when the hapless Elyon is sucked into the lake at the end of the episode (via another decent inlay shot).  Antodus complains to his brother Ganatus that they’re all doomed, doomed (a theme which will continue into the next episode).