A criminal gang descends into the sewers of Paris, uses an interior exit to get their hands on a safe and move it out of town, where they work to open it.
The passage of time in this movie will seem odd to the modern viewer, and even odder to those of us familiar with theatrical and literary works from the period. The film makers use editing to cut out large sections of time; thus we don't see the crooks while they are moving the safe out of town so they can work on opening it at their leisure. Yet within the shots, there is no saving of time -- because each scene is a single camera set-up. The scene does not even end until everyone who is going to move out of camera range has done so, and they never open in medias res.
Thus, in one scene, we see the safe appear out of a window, and lowered to the ground. Then the eight or nine people who accomplish this stand around while a cart comes in from offscreen. They load the safe on it, and it exits the frame, followed one by one, all of the people. Finally there is a cut..... and here they all enter the frame somewhere out of town.
Clearly the film makers understood that the trip from one spot to the next isn't very interesting, but this tendency to show everything in a scene persisted a long time, even after the introuction of Academician editing. I've seen B westerns from the middle of the 1930s in which we get to watch a character enter a room, hold a conversation, and exit a room to no purpose save to lengthen a second feature by half a minute. It wasn't needed in 1935, and it wasn't needed here.