The film opens with several police officers dragging Sid Vicious (Oldman) out of the Hotel Chelsea following the death of his girlfriend, Nancy Spungen (Webb). Vicious is soon driven to a police station and upon arrival is asked to describe what happened.
A few years earlier, Vicious and Johnny Rotten (Andrew Schofield) meet Spungen, a groupie who has come to London to bed The Sex Pistols. Vicious dismisses her at first, but starts dating her after she sells him heroin; it is implied that she introduces him to the drug. The two fall deeply in love, but their self-destructive, drug-fueled relationship frays Vicious' relationship with the rest of the band, which eventually breaks up in the midst of a disastrous American tour.
Vicious attempts to start a solo career with Spungen as his manager, only to be dismissed as a has-been. By now, both he and Spungen are heavily addicted to heroin, and Spungen has spiraled into a deep depression. It ends tragically one night when, during an argument in which Vicious announces his plans to stop using heroin and return to England, a suicidal Spungen begs him to kill her. They fight in a drug-induced haze, and he stabs her, although whether or not it was intentional is left to interpretation. They fall asleep and later Spungen awakes and stumbles into the bathroom, where she collapses and dies.
Vicious is released on bail. While on his way home, he sees a vision of Spungen waiting for him in a taxi; he gets in and they embrace, reunited. The postscript then says that Vicious died of a heroin overdose: "Nancy and Sid R.I.P."
The film is largely based on the mutually destructive, drug-and-sex filled relationship between Vicious and Spungen. Vicious' mother, Anne Beverley, initially tried to prevent the movie from being made. After meeting with Cox, however, she decided to help the production. Some of the supporting characters are composites, invented to streamline the plot.
Oldman lost weight to play the emaciated Vicious by eating nothing but "steamed fish and lots of melon," but was briefly hospitalized when he lost too much weight. Vicious' mother, Anne Beverly, also gave Oldman Vicious' own heavy metal chain and padlock to wear in the film.
Courtney Love recorded an infamous video audition in which she exclaimed "I am Nancy Spungen." Cox was impressed by Love's audition, but has said the film's investors insisted on an experienced actress for the co-leading role. Cox would later cast Love as one of the leads in his movie Straight to Hell. Instead Love was cast in the relatively minor role of Gretchen (a part that Cox wrote specifically for her benefit), one of Sid and Nancy's New York junkie friends. Ironically, Love would be compared to Spungen later in life on account of her marriage to Kurt Cobain.
In his 2007 autobiography, Guns N' Roses guitarist Slash revealed that the casting director hired all five members of Guns N' Roses as extras for a club scene, having coincidentally scouted them in different locations without their knowledge. He said "all of us showed up to the first day of casting, like 'Hey...what are you doing here?'" However, Slash was the only one in the group to stay the entire shoot.
Webb and Oldman improvised the dialogue heard in the scene leading up to Spungen's death, but based it on interviews and other materials available to them. The stabbing scene is fictionalized and based only on conjecture. Cox told the New Musical Express: "We wanted to make the film not just about Sid Vicious and punk rock, but as an anti-drugs statement, to show the degradation caused to various people is not at all glamorous."
The original music is by Pray for Rain, Joe Strummer and The Pogues.
The film was rated R in the US for drug use, language, violence, sexuality, and nudity. Prominent musicians made appearances in the film, including: Iggy Pop, Nico, Courtney Love, The Circle Jerks, and Edward Tudor-Pole, of Tenpole Tudor. The film was originally titled Love Kills.