The Policeman of the 16th Precinct

Three friends want to find some money. When they are at a cafe, they think of a nice plan: one of them will go to a house of a rich man and steal some jewels, while the other will watching so none sees the robber. He also has the idea to be dressed as a policeman so nobody suspects him. The plan is working perfectly, except for that a woman thinks that he is a real policeman and calls him to her house to investigate about a missing ring