This fourth entry in MGM's Thin Man series could just as well have been titled "Nick and Nora Charles Go to the Races". Officially retired from sleuthing, Nick Charles (William Powell) does his best to be a dutiful husband to his lovely wife Nora (Myrna Loy) and a good father to his young son Nick Jr. (Dickie Hall). But when murder rears its ugly head at the local race track, Nick is called in by Major Jason I. Sculley (Henry O'Neill), head of the New York athletic commission, to help solve the case. As usual, there is no shortage of suspects: This time the "rogue's gallery" includes high-rolling gamblers Link Stevens (Loring Smith) and Fred Macy (Joseph Anthony); Link's hoity-toity girlfriend Claire Porter (played by legendary acting teacher Stella Adler); two-bit tout "Rainbow" Benny Loomis (Lou Lubin); reporters Whitey Barrow (Paul Kelly) and Paul Clarke (Barry Nelson); and Clarke's sweetheart Molly Ford (Donna Reed). Highlights include a zany episode on a department-store merry-go-round, an outsized brawl at a fancy sea-food restaurant, and the inevitable gathering together of suspects in the offices of police lieutenant Abrams (Sam Levene). The flippant nature of Shadow of the Thin Man can be attributed to screenwriters Irving Brecher and Harry Kurnitz, both longtime friends and associates of comedian Groucho Marx.
by Hal Erickson synopsis