Meek and mild-mannered college professor Clifford Skridlow is inadvertently thrust into the dangerous and colorful world of Chicago's underground when he meets a fast-talking pimp named Smooth Walker. Smooth convinces Clifford to take his place as the mob threatens to collect on his substantial debts. Clifford reluctantly agrees, assuming the flamboyant and fictitious persona of "Doctor Detroit," a crime boss invented by Smooth. Clifford now must navigate this seedy underworld while simultaneously maintaining his respectable life as an academic.

Clifford's double life grows increasingly complicated as he juggles responsibilities at the college, interactions with local gangsters, and handling the needs and whims of Smooth's stable of escort workers. He finds himself facing off with a ruthless mob boss, known as Mom, who seeks to exert control over the city's criminal enterprises. In his quest to protect his new friends and preserve his own identity, Clifford discovers hidden reserves of courage and wit, all while trying to keep his ludicrous alter ego from being exposed.