Chicago, January 1933. Danceland has a big sign, ""30 girls, open until 2 a.m."" Inside, customers mingle with the dime-a-dance girls. Hoofer Ellie Haskell says goodnight to the owner, Marty Pulaski; outside, she is immediately shot by a sniper on the roof of a building across the street-- the sniper is Herbie Pulaski, Marty's mentally disturbed brother. Lt. Roy Gunther is on the case, he questions Marty, who has 20% of the dancing racket. However, Marty is sure his main competitor, Vince Bogan who owns 80% of the dance racket, is responsible for the killing.