Janet Leigh is featured as party girl Ivy Conrad, and Edmond O'Brien as a gangster who applies pressure to Kelly.

Peggy Lee portrays alcoholic jazz singer Rose Hopkins (a performance for which she received an Academy Award nomination for Best Actress in a Supporting Role).

Jazz cornetist Pete Kelly (Jack Webb) and his Big Seven are the house band at the 17 Club, a speakeasy in Kansas City in 1927 during Prohibition.

Crime boss Fran McCarg (Edmond O'Brien) is moving in on the local music scene and wants a percentage of the band's meager earnings.

After the night's last set, Rudy, the club manager, orders Kelly and the band to the mansion of Ivy Conrad (Janet Leigh), a wealthy flapper with a reputation for hosting rowdy parties.

Kelly and his band are run off the road by unknown assailants as they drive back to town and Firestone is thrown out of the car over its hood.

Tired and frustrated by his drummer's murder, and the subsequent departure of his long-time friend and clarinetist, Al (Lee Marvin), Kelly returns to his apartment to find Ivy asleep in his bed.

Bettenhauser then tells Kelly he can find incriminating bank checks and papers in McCarg's office at the Everglade Ballroom.

Kelly rifles a desk in McCarg's office, but before he can get what he needs the ballroom's riotous orchestrion begins to blare; Ivy is there, insisting on her dance.