Traffic in Crime (movie, 1946)

Police Chief Jim Murphy, in a crime-ridden city, deputizes newspaper-reporter Sam Wire, to work as an undercover operative to rid the town of the gangster element. Sam taunts and tricks the two leading gangsters, a mob girl, 'Silk" Cantrell, and a bribe-taking police official, into setting ambushes and death-traps for him, which backfire on them, and achieve his assignment directive.