Airdate: August 15, 1964
Starring William Hartnell, Carole Ann Ford, William Russell and Jacqueline Hill
Written by Dennis Spooner
Produced by Verity Lambert
Directed by Henric Hirsch
There are three major plot threads running through this episode, one involving the Doctor, one Ian, and one the others. The Doctor makes his way on foot toward Paris to rescue his imprisoned friends. This plotline is treated lightly, with a comic touch, as the DOctor gets press-ganged into a work crew and escapes ingeniously (and knocks the boss out by hitting him with a shovel, which isn't the sort of the thing the Doctor is normally seen to do). The others, however, face rather more grim circumstances.
First of all, you don't have to read between too many lines to see that the jailer at the Conciergerie Prison is offering to help Barbara escape in exchange for sexual favors. That's the kind of grittiness we're dealing with here, as she and Susan are trapped in a dank, rat-infested cell. Meanwhile, Ian (who, along with his cellmate Webster, never appears on screen with anyone else... perhaps William Russell pre-filmed his scenes to allow for a week-off, but I don't know) makes a promise to his dying cellmate to find British spy James Stirling. This is the first inkling we've had of a story beyond "how will the heroes escape to the TARDIS?"
Notably, this episode is the first in the show's history to utilize location shooting, and even more notably, none of the main cast are involved. For shots of the Doctor walking to Paris, a double was employed to copy Hartnell's distinctive gait on location. It won't be until Season Two that the regular cast gets to venture outside the confines of the studio.