Do you mean the old 1929 American film The Locked Door? No, this isn't based on a true story as far as is known. It's adapted from a stage play called The Sign on the Door, from the playwright Channing Pollock, who also wrote many other successful plays and shows including the Ziegfield Follies.
It does have a real-life background in that the main events of the film and play are structured around Prohibition. This was a real life law that existed in the US from 1919 to 1933, forbidding the sale of alcohol. This caused all kinds of underworld and criminal activity, and changed the lives of many ordinary citizens who tried to get round the law in various ways. One such way is what happens at the start of The Locked Door, when the characters go out on a 'rum boat' which was a ship that had to be more than 12 miles away from the coast in order to sell alcohol legally.