When New York police commissioner Lewis J. Valentine instructed his men that the best way to handle criminals was to "muss 'em up," he probably had no idea that he was supplying the title for this RKO Radio crime drama. It all begins when millionaire Paul Harding's (Alan Mowbray) dog is murdered. This might have merely been a case for the ASPCA, but it soon leads to a kidnapping, an exorbitant ransom demand, and a murder. Turns out that the whole plot was concocted by Nancy Harding (Molly Lamont), who's been posing as the millionaire's long-lost daughter, and by a mysterious mastermind whose identity won't be revealed here. Preston S. Foster, as New York detective Tip O'Neil, solves the case. Based on the novel The Green Shadow, Muss 'Em Up was released in Britain as The House of Fate.