Hard-boiled detective Dick Tracy (Warren Beatty) is searching for evidence that proves Alphonse Big Boy Caprice is the city's most dangerous crime boss. He may have found the key to unraveling the crimelord's illegal empire in Breathless Mahoney (Madonna), an enigmatic barroom singer who has witnessed some of Caprice's crimes firsthand. However, she seems more set on stealing Dick away from his girlfriend, Tess (Glenne Headly), than helping him solve the case of his career.