Thin Ice is an episode of Doctor Who very clear in its purpose. It gave us a power interaction between Bill and the Doctor, and notched the Nardole / vault story forward. Everything else was secondary to this, though very attractive and well-realised it was. Of the three episodes so far it is my favourite, which is not to say I wouldn’t have enjoyed a decent story as well.
The story (such as it was)
It’s the Frost Fair of 1814 and street urchins abound. There’s something under the ice and its waste can be used as super fuel to power industry. Cue the workhouse and evil Lord Sutcliffe, along with strange Jules Verne style diving costumes. A bit of digging around, a confrontation and some explosions to sort everything out.
Away from the Doctor beating up (literally in one scene) the villains, there are two key scenes, Bill asking the Doctor about death and murder, and the Doctor’s speech about judging the human race by its treatment of others. The end does not justify the means (and this is an echo of the Matt Smith story The Beast Below) but the Doctor needs instruction from Bill (weirdly) to save the day.
Even full of generic (though racially well-balanced) characters, the Frost Fair is a wonderful setting I am sorry to see destroyed. The Doctor was careful to admit to several visits, protecting continuity (eg with the Big Finish story Frost Fire). Sarah Dollard really captures a location even if the storytelling was smothered in exposition. This wasn’t a drama but a set of key events, so shortcuts were taken to get the narrative out of the way.
I did think the resolution was too fast as the Doctor could escape, get his suit on, move the explosives (and the detonator wasn’t yet invented) and do everything in the short time he had while Bill wandered around.
More pedantically the diving suits annoyed me. I did see the air tubes this time, but where was the air pump and who was making it work (and what did it use for an engine). Also how did they move around if the ice froze after they penetrated? Wouldn’t the tube get frozen?
So, some gripes, but actually I liked a lot things about this. Over to you…