Maestro's music creates mindless puppets, who commit crimes at his command. To lure the sinister jewel thief out of hiding, Pinkerton Agent Sadie Michelson poses as a wealthy widow. Fearing for her safety, William "Cass" Cassidy, her hotheaded lover, hatches his own plot to end Maestro's killing spree. But his daring gamble backfires and costs him Sadie's trust. Now Cass is on the run, hunted by Maestro and the Pinkertons. Torn between her mission and her gunslinging lover, Sadie must stop Cass's showdown with Maestro, or she'll lose her badge--and her man.