Radio disc jockey Johnny Laurence receives a letter informing him that his proposal for a music show has been rejected by middle-aged television producer Paul Selway.
At a radio studio off Oxford Circus, Johnny presents his record show 'Discology', but he doesn't really 'get' rock'n'roll. His more 'hep' studio assistant, Pete, tells him about this exciting new live music for dancing, and invites Johnny and his girl Carol to accompany him and Jackie to the Empire Rooms - a large dance hall with rock'n'roll bands. Carol (who works in a stuffy solicitor's office) is a bit 'square' but agrees, and the foursome meet up outside the venue. Pete and Jackie show them what the new music and dancing is all about and Johnny and Carol get dancing.
Johnny and Pete visit Jackie at the Chimes Music Store, where she sells many rock'n'roll records. Pete (aided by Jackie) explains the excitement of rock'n'roll music to Johnny - "You need one for the message, Two for the blow, Three for the benzedrine, And then you Go, Man, Go!"
Johnny is so impressed with the energy of the music and dancing that he decides to stage a rock'n'roll showcase at the ballroom to impress Selway, and calls into the latter's office to tell him about his plans. Drawing on Jackie's listing of best selling rock'n'roll performers on record (such as the Art Baxter and Tony Crombie groups), Johnny visits the office of 'Kruger Enterprises' in Cambridge Circus to book acts. The musicians assemble and play at a rehearsal room. Johnny is so busy that he has to abandon a pre-booked cinema date with Carol. She is upset but goes to the film with Jackie instead. After leaving the cinema, the girls pass the Brazil Expresso Bar where Carol sees Johnny engaged in intense conversation with a pretty girl. Not realising that she is actually a singer he is booking for the show, Carol becomes upset and sulks, despite an apologetic phone call from Johnny.
At the Empire Rooms, Selway and his fawning personal assistant arrive, and compère Tony Hall introduces the acts. During the show Carol sneaks in unseen but leaves early. Some rock'n'roll numbers seem to have a strange effect on Selway, who holds his hand on his heart in a manner that suggests a heart attack, but at the conclusion he makes a generally favourable comment to his assistant and to Johnny. That evening, a distressed Johnny plays a record of a romantic ballad ('Cry Upon My Shoulder') and imagines dancing with Carol.
Selway agrees to produce a series of eight rock'n'roll television shows. Their problems resolved, Johnny and Carol are united, and at the Brazil Expresso coffee bar, singer George 'Calypso' Browne sums up Johnny's story. Art Baxter and his musicians arrive and perform 'Rock You Sinners', as Johnny, Carol and Pete and Jackie jive to the music.
