After arriving at the last London Frost Fair, the Doctor and Bill investigate mysterious disappearances…

Sarah Dollard’s first script for Doctor Who had the difficult job of writing Clara out of the show – and I suspect I’m not the only person who wishes that that had been the case, and the sacrifice we saw in that episode stood. This time, she’s introducing Bill to the joys of TARDIS travel to the past, and, as with the first two episodes of the season, there are plenty of questions for the new traveller to pose – this time getting to the heart of the moral dilemma that would face anyone in that situation. As we’ve seen in the trailers, Bill doesn’t pull her punches (nor does the Doctor at one point in the episode!), and the titular Thin Ice certainly doesn’t just refer to the state of the River Thames.

Peter Capaldi is simply brilliant in the story, given plenty of opportunity to show the Doctor’s righteous anger and acceptance of who and what he is, while the Time Lord’s relationship with Bill is one of the best we’ve seen in the show in recent years. (It’s again something of a Nardole-lite episode, but the scenes in which Matt Lucas does appear move a number of plot strands forward.) Pearl Mackie continue to flesh out Bill, whose self-awareness is one of her charms; there are quite a few lines that could easily have fallen flat but Mackie finds the right level of bravado and curiosity.

Once again, the story is pretty straightforward and while there are overarching plotlines, each episode so far has been self-contained. There’s a definite feel of the very first year of the rebooted show, not least in the “present, future, past” settings of the opening trilogy – and in a very interesting reflection of a key point from one of the mid-season stories that year, and the group dynamics from a later one. New-to-Who director Bill Anderson gives the episode a definite sheen – this isn’t the down and dirty 1814 of Tom Hardy’s recent series – and keeps everything moving at a slightly faster pace than we’ve had so far this year.

Verdict: A terrific first trip to the past for Bill 9/10

Paul Simpson