The only significant bit of this week’s plot feature William Russell, on film, before he went away on holiday (making him and Carole Ann Ford the only two regulars to have appeared in every episode to date). Ian is entrusted with a dying man’s secret: find the spy James Stirling and warn the English government of French war plans.

The rest of the episode focuses on Barbara and Susan miseries at the hands of the Conciergerie Jailer and some rats, and the Doctor’s adventures on the road to Paris. The Barbara and Susan scenes are interesting in that Barbara once again becomes the victim of the unwanted advances of an uncouth northerner (just as in Terry Nation’s The Snows of Terror), and later proves her practicality once again when she looks to find a way out of the cell. This contrasts with Susan’s defeatism: ‘We can’t go on being lucky. Things catch up with you.’ It’s either another hint that Susan is tiring of her life of adventures, and foreshadowing her departure, or an indication that Spooner thinks she’s useless. Sadly, Barbara also gets sucked into Susan’s mood hoover, finally preferring to be decapitated than deal with a few rodents.

The Doctor scenes are much better, and immense fun. Hartnell’s comedy experience is utilised as never before in the series as he mobilises a group of tax dodgers to outwit a greedy works’ overseer. Given he’s often thought of as frail and decrepit, Hartnell’s talent for physical comedy is surprising: he has the look of Buster Keaton as he’s ordered to start digging rocks with the chain gang. He also gets some brilliant Spooner dialogue:

Overseer: I suppose you think you’re very clever.

The Doctor: Well, without any undue modesty, yes!

The sequence ends with the Doctor finally following through on The Forest of Fear and bashing an antagonist over the head – but Henric Hirsch makes sure we see the Overseer snoring peacefully, and the comedy of the moment is preserved.

These are thoroughly entertaining scenes, but they’re not even the best Hartnell moment of the episode. That comes near the start, when the Doctor thanks Jean Pierre for saving him from the burning farmhouse. Offered the chance to escape, the Doctor doesn’t consider it for a second. ‘I must rescue my friends,’ he declares. Then, in my new favourite Hartnell moment, he says farewell to the boy with a little salute: ‘Au revoir, Monsieur Captain.’ It’s a gesture you can imagine one of the modern Doctors making, and a really lovely and lovable bit that’s indicative of how much the Doctor’s softened since the abrasive and suspicious character of the start of the series.

Behind the scenes, this apparently was quite an unhappy episode to make. But none of that makes it to the screen. Hirsch’s direction is quite imaginative, with engravings of Paris (an idea later re-used in the next Paris-set adventure), and a neat cut from Barbara digging her way out of a prison cell to the Doctor digging up the road. There’s very little actual plot to the episode, but it’s entertaining enough, and with enough obvious peril (the guillotine slicing down at the head of the episode, and Barbara and Susan being carted off to it at the end) that this hardly seems to matter.

Next episode: A Change of Identity