Billy Martin, whose band is rebelling against him for lack of paying gigs, scores an important audition with Joe Corwin, who is opening a new club and needs a premier act. Corwin's constant companion Helen shares his immediate fondness for the band, on the basis of just the title song "Rhythm in a Riff." When Billy Martin falls in love with Helen, it looks like a bad thing that could get in the way of the band's success. Fortunately, as eventually revealed, Helen and Joe are not to be romantically involved at all; they're merely great friends. The bulk of the rest of the film consists of the musical performances done for the opening night in Joe's new club.