Shadow of the Thin Man (1941)

Nick and Nora's hopes for a pleasant afternoon at the local race track are dashed when a jockey is found shot dead in the locker room. Nick's friend Lt. Abrams wants him to help out but Nick is enjoying the good life too much to get involved. However, he is subsequently approached by Major Scully to look into corruption and the role of organized crime in gambling. Others are killed but in the end, Nick gathers all of the suspects into a room and identifies the killer.