The film depicts the rise and fall of Kate (Hazel O’Connor), an angry but creative young singer and songwriter. At the beginning of the film, she is discovered by Danny (Phil Daniels), a young man who desperately wants to become a promoter of music bands but is stuck working for another agent (who forces him to buy hundreds of copies of the singles of one of his artists, Suzie Sapphire, to fix the music charts). Danny takes an active part in controlling Kate’s career, impressed with her talent if not her band, whom he promptly fires. He arranges auditions and reaches out to former friends, and in doing so Kate’s new band, Breaking Glass, is formed. Breaking Glass consists of Kate on vocals and keyboard, best friends Tony (Mark Wingett) and Dave (Gary Tibbs) on lead and bass guitar respectively, the drug-addicted and partially deaf Ken (Jonathan Pryce) on saxophone and the ‘mental’ Mick (Peter-Hugo Daly) on drums.
Danny does his best to promote the band but finds it hard-going. The best he can do is several nights in a pub frequented by neo-nazis, which, given Kate’s anarchist and liberal tendencies that shine through in her songwriting, doesn’t go well. After a brawl breaks out one night and the publican refuses to pay the band, Danny finally manages to persuade the anti-establishment Kate to record a demo tape. Danny and Kate then take the demo tape to a gig promoter who shows no interest.
The band keeps struggling to get by, despite being hassled by the police, and in the meantime Kate realises she is falling in love with Danny. The hard work eventually pays off when the gig promoter finally agrees to help out, but only by offering the band a contract that Danny describes as “feudal”.
Several months pass as the band tours the country, building up a large fanbase. On Christmas Eve the band is stranded when their van breaks down and the British Rail train drivers are on strike. It is at this point that Danny and Kate have sexual intercourse for the first time and become a couple.
Danny blackmails his former employer (by threatening to reveal how he paid Danny to rig the charts) into attending a gig in London. However, disaster strikes when the band begins to perform and a power-cut occurs. Encouraged by Danny and Mick, the band continues anyway and wins the hostile crowd over. Their performance greatly impresses the music agents Danny forced into coming, and the band is offered a record contract.
Almost immediately things do not go well. Firstly, the band are not amused by how the music agents demand changes to some of the ‘offensive’ lyrics to secure airplay (such as changing ‘kick him in the arse’ to ‘punch him in the nose’). The recording of the first album does not go well and the agents also reveal that they think Danny is the problem. The chart rise of “Top of the Wheel”, the band’s first single, parallels the earlier success of Suzie Sapphire.
Forced into playing at an anti-establishment benefit concert, the band finds the organisation lacking and tries to leave, only to see a neo-nazi rally approaching. They decide to play anyway (and a particularly controversial song), which results in a riot breaking out. Danny wants the band to leave but Kate insists on taunting the crowd. That changes when a young man who has been stabbed falls right in front of her, screaming in pain and desperation. This causes Kate to scream.
While recovering, Kate is forced to audition for a famous music manager, Woods (Jon Finch), who makes it clear that he wants to produce her music and also be involved with her. Kate’s new songs seem to help her recover mentally, but the rest of the band are not so happy. Danny finds himself being pushed more and more into the sidelines and Ken has no part to play on the big new single.
On tour again, the agents start sowing seeds of discontent among the band, hinting heavily that Danny is the problem. This leads to a confrontation on the tour bus after which Danny storms out and quits. Woods now moves in as the band’s manager and becomes Kate’s new lover.
After much more success, including a platinum record, the band keeps falling apart. Mick quits, claiming to be bored. Kate hates the pressures and lack of control that fame has brought her. Dave and Tony treat Ken terribly, hating him for being a junkie, and force him to quit the band too. By now the band’s name has changed to Kate & Breaking Glass.
During a radio show which invites listeners to call in, Kate has trouble understanding her fans and gets angry when she is accused of being controlled by her record company, and even more so when someone she thinks is Danny calls in to accuse her of selling out. The next single released is “Big Brother”, which features the ‘offensive’ lyrics completely changed as the music agents originally wanted, proving she has indeed sold out.
Mick and Ken meet with Danny and accuse him of abandoning them and ruining the band. But all the same they plead with him to come back and help Kate, but he refuses.
The film ends with a huge concert and the debut of a new song, although already drugged Kate is forced to go on stage by Woods, who forcibly holds her down while a doctor injects her with more drugs. Kate goes on with the band, performing the song “Eighth Day” (the US release of the film ends the movie after the song). After the song Kate flees the stage into the London Underground, where she begins hallucinating people dressed as her and her former bandmates, and has a nervous breakdown.