Detective Hank Hyer and reporter Sim Perkins of The Star are nearly evicted from Twitchell Arms apartments. Hank then needles Silas Wagon, who is running for mayor, into hiring him to help him defeat incumbent Callaghan, a grafter, who is running a crooked campaign. Next, Odette La Vin checks into Twitchell Arms with ex-con Nick Mazaney in order to blackmail Wagon with a bigamy scandal by claiming she is his daughter. However, Callaghan, who hired Mazaney to get rid of Wagon, realizes Mazaney might get a higher price from Wagon by letting him win the election and has him arrested. Odette goes ahead with her scheme, however, and gives Wagon one day to come up with $10,000. Hank then gets Sim drunk to land him in jail with Mazaney and interview him. Odette makes her move during a campaign speech, calling Wagon "father" and getting her story in the newspapers. Callaghan is confused because he knows Odette is not on the payroll. Hank then makes a speech to Wagon's constituents about the cause being "greater than any individual," making a case for Sim to run for mayor on the laurels of his editorials, which have been criticizing Callaghan and his grafters. In jail, meanwhile, Sim offers his cold medicine to Mazaney, who apparently falls dead. Sim is accused of murder until Hank discovers a poisoned cigarette butt in the cell, which was delivered by a messenger to Mazaney. The messenger identifies Wagon as the murderer, but Hank proves the cigarettes came from Odette. Mazaney then recovers and the police arrest Odette for a string of crimes perpetrated across the country. Sim runs for mayor against Callaghan and wins, but, much to Sim's relief, Callaghan reveals that Sim is a Canadian citizen and kicks Hank out of town.