It's Prohibition, and the boys wind up behind bars after Stan sells some of their home-brew beer to a policeman.
This 'prison'-focused full-length film--the first by Laurel and Hardy--was a ton of laughs, as they bring their unique brand of hijinks to such aspects as a hilarious loose tooth of Stan's causing him to make the worst possible sounds at the most inopportune times, and walking-on-eggshell relations with their cellmate, the infamous 'Tiger'. Very good and consistently re-watchable--even if it pales in comparison with their later movies.