Soho, London 1958. The bustling night-time streets, with expresso bars, amusement arcades, strip clubs and street entertainers, contain many colourful characters. One is cynical, fast-talking Johnny Jackson, a drummer and small time agent trying to persuade reluctant coffee bar owners to book his teenage rock n' roll acts.
Johnny's live-in girlfriend, Maisie, works as a stripper in a non-stop nude revue but has ambitions to be a singer. After work, Maisie takes Johnny to a basement club, the 'Tom Tom', where a beat group is playing and a youth plays the bongos and (reluctantly) sings. Johnny is mightily impressed - the youth's name is Bert Rudge and he works at a nearby arcade. Johnny wants to sign him, and visits his dysfunctional family home in an East End tenement, but Bert's parents refuse to agree terms.
Nevertheless, Johnny proceeds to offer Bert a 50/50 contract, and a new name: 'Bongo Herbert'. Johnny visits Mayer, Garrick Records' artist and repertoire manager, and arranges for him to visit the club to see Bongo perform. Mayer's preference is for opera and old-fashioned stars, and he is preoccupied with promoting his old client Dixie Collins, a middle-aged US singer whose career is on the slide, who he has booked for a British television special.
BBC television cameras are filming in Soho for a documentary series, Cosmorama, about teenage rebellion. Johnny collars Gilbert Harding and persuades him to take the film crew to 'where the young relax' after hours. With TV crew and Mayer in attendance, Bongo sings 'A Voice in the Wilderness'. Mayer says young rock 'n' rollers merely give him 'nausea' but he can see there is a market for this stuff, and offers Bongo a recording contract; the record sells well. Johnny takes part in a TV panel discussion with a vicar and psychiatrist.
Dixie arrives in London and entertains the press at a Dorchester Hotel reception - her old fashioned glamour is clearly past its 'sell by' date. Johnny gets Bongo booked for a spot on Dixie's TV special, and for his next recording Johnny suggests a song combining motherhood and religion. Bongo makes a big impression with 'Shrine on the Second Floor', featuring a church choir. Bongo is also a hit with the young debutante set, who visit his dressing room. Dixie invites Bongo for an after-show drink and entertains him in her suite, but in the press reviews the next day all attention is given to Bongo. Dixie hears of Bongo's 50/50 deal with Johnny, and passes this information to Mayer.
Maisie is by now feeling neglected, resenting the amount of time that Johnny is spending with Bongo. Johnny arranges a northern variety tour, but the older, more experienced Dixie is aware that Bongo could revive her career with a joint appearance in New York, as well as rejuvenate her waning physical powers. Dixie 'looks after' Bongo, but Johnny resents Dixie's influence and tries to take him back.
Dixie decides to check out Bongo's contract herself and arrives by chauffeured car at the Rudge family home. Bongo's mum says she did not agree to any contract and will never sign one, which means that, as Bongo is under 21, Johnny's 'contract' is illegal. Dixie tells Mayer to get his lawyers on to this. Mayer tells Johnny that, as he can no longer deliver, his stake is worthless; he can now take over management of Bongo himself. He then receives a phone call to say that New York wants to book the 'new sensation' Bongo - but without Dixie.
Johnny, his management plans ruined, takes out his drums for a band tour to Manchester, and Maisie sees him off. On the street he is approached by a film producer chum, who enthuses about his new project 'Omar Khyyam' and needs a leading lady who can sing. It so happens Johnny has just the girl who would fit the bill perfectly, and he has her under personal contract. Her name is... Maisie.
