Shadow of the thin man (1941)

While attending a major horse race with their young son, Nick Jr., Nick and Nora Charles witnesse a shocking murder from the crowded grandstand. What first appears to be an isolated killing soon leads to a maze of corruption, blackmail, gambling scandals, and criminal intrigue. As Nick investigates, he encounters suspicious bookmakers, dishonest officials, rival gangsters, and a mysterious killer determined to stay ahead of the law. Nora, as always, is never far from the action, bringing her quick wit and fearless curiosity to the case.