 Michael Shayne (Hugh Beaumont) accepts an assignment to investigate a gang of pari-mutuel race tickets counterfeiters over the protests of his secretary, Phyllis Hamilton (Trudy Marshall), who wants him to join her on a vacation. Shayne contacts Mayme Martin (Claire Carleton) who offers him information, and sends his friend Tim Rourke (Charles Mitchell) to get it. Tim arrives to find Inspector Rafferty (Ralph Dunn) there as Mayme has been murdered. Shayne has gone to the race track to see Jim Payson (John Hamilton) and Al Hardeman (Grandon Rhodes), the operators. Two thugs, Joe (Frank Hagney) and Punk (Maurice B. Mozelle), take shots at Shayne and he is wounded. He later learns that a printer, Madden (Ben Welden) and his engraving foreman Edwards (Byron Foulger) served time for counterfeiting Irish sweepstake tickets and Shayne thinks he has the case solved...until Madden and Edwards turn up murdered.