It appears that while Lucien was inspecting the machines in this steampunk looking factory, a few lose threads got caught on one of them, and as they were turned on, they started to slowly unravel his clothes, he didn't notice for a while, but by the time he did, most of his pants has been eaten up! exposing his diaper, he tries to make a dash for the off switch, but is instead dragged further away towards the machine!
(Don't worry, those massive rollers won't hurt Lucien. Worst thing that could happen is for the thread to be completely unraveled and leave him mostly clothing-less.)