November 1963. On the day of the Kennedy assassination, Jim Maclaine wanders around a fairground with his former colleague Mike, who he's trying to persuade to become the road manager for his band, the Stray Cats. Mike claims that he's not clever enough, but eventually accepts the job.

He has a natural talent for it, successfully negotiating a refund from a club manager, arranging living and rehearsal space from a local launderette tycoon, and securing Jim's band a top-of-the-bill booking at a university. While Jim seduces the twin blonde singers of the supporting act, Mike listens to a boxing match on the radio. He criticises Jim for not taking the job seriously, and advises him to drop Johnny Cameron from the band.

The band have a meeting with a big music publisher, which leads to a recording contract, though the company retains publishing rights, something Mike is powerless to oppose. During the recording session, the producer suggests recording a track without Johnny, saying that it will be the B-side of their debut single. Later, a clearly disgruntled Johnny has an argument with Mike about expenses.

At a music industry garden party, Mike arranges an interview with the Evening Standard and persuades a top DJ to play the single. The band listens to his radio show, and Johnny is furious to hear that what he thought was the B-side is in fact the single itself. He is equally annoyed at the Standard's full-page interview with Jim.

The band, now called Jim MacLaine and the Stray Cats, appears on television, performing to screaming hordes. Mike and a record company executive ask the director to focus on Jim at the expense of Johnny. After the single reaches number one in Britain and number 18 in the US, Johnny is quietly fired by Mike.

The Stray Cats tour America. Jim gives an interview to CBS in which he calls for the legalisation of drugs and the abolition of marriage. The band meets its new American manager, Porter Lee Austin, who, without Jim's knowledge, purchased 75% of their rights from their UK publishers.

Despite their new life of luxury, both Jim and the band are frustrated. When asked in an interview what he thinks of America, Jim says that he hasn't had a chance to see it, while the band complain that he's getting all the attention. Austin's accountant uncovers a tax concession for registered religious charities and suggests the band performs religious material.

During a poolside discussion and subsequent dinner, Jim is appalled to hear that Austin has discussed releasing an album before Christmas, which will mean writing an unrealistic amount of new material. He storms out of the room and Mike has to calm him down, explaining that music is as much business as art form. Later, his girlfriend Danielle tells Jim that the band is near mutiny, and that he needs them more than he thinks. They are interrupted by the news that Jim's mother has died.

The solemnity of the funeral is wrecked by hordes of fans and photographers. Jim shares a hearse with his ex-wife Jeannette and son and her new boyfriend. Jeannette is furious that all her attempts at anonymity have come to nothing.

Austin discusses Jim's future with Mike, suggesting that Danielle is a bad influence on him. Behind the scenes machinations lead to Jim and the Stray Cats separating, with Austin managing both. Mike justifies this to Jim by saying that the band was dragging him down.

Jim writes an ambitious operatic piece about the deification of women. Shortly after the recording, he breaks up with Danielle - to Mike's delight. But the pressure is starting to crack Jim up. He buys a castle in Spain and moves in with Mike. There, he watches old footage of the band and becomes increasingly reclusive. His experiments with drugs have fatal consequences for his beloved dog.

Two years later, Austin flies to Spain to persuade Jim to return to performing, warning that his taxes will soon outstrip his royalties. Jim reluctantly agrees to give a live TV interview, but deliberately sabotages it before collapsing mid-sentence from an overdose. In the ambulance, Mike pleads with Jim not to die.