In 1976, thirteen-year-old Christiane Felscherinow lives with her mother, younger sister, and her pet cat in their small apartment in an unkempt multi-storey, concrete social-housing building in a dull neighbourhood on the outskirts of West Berlin.
As she falls in love with Detlev, Christiane begins using heroin on a regular basis in order to be close to him, gradually becoming more and more dependent on the drug until she is a full-blown addict.
After her 14th birthday, Christiane stops going home and spends more and more time at her cohorts' unkempt apartment; she is also drawn to Bahnhof Zoo, a large train and subway station notorious for the drug trafficking and prostitution that takes place in its underpasses and back alleys.
Christiane also starts to prostitute herself, imitating Detlev, who sells sex favours to male clients on a regular basis in order to support his heroin addiction.
After being discovered unconscious on the bathroom floor at home due to a heroin overdose, Christiane tries going cold turkey with Detlev, an excruciating experience for both of them.
She returns to the station in order to find Babsi, only to discover that she is dead of an overdose at barely 14 years old, as plastered all over the front pages of many newspapers.
Real life "Stella" (Catherine Schabeck), aged 18 at the time, has a short cameo as the drug dealer that sells the first dose of heroin to Detlev.
In the scene where Christiane runs through the alleys of the station to find Babsi, the camera lingers on several drug users leaning against the walls of the underpass.
In a 2011 interview, Thomas Haustein, who played Detlev and was still in school at the time, recalled how terrified he felt being surrounded by real-life addicts, but that he was able to successfully copy their behaviour for his character.
Bowie's music from his albums made in West Berlin during 1976 and 1977 is played throughout the picture, and as he was at the peak of his popularity during the late 1970s and early 1980s, his presence helped boost the film's commercial success.
In one particularly disturbing scene, a junkie climbs over a public toilet stall to steal Christiane's fix, inject himself in the neck, hand back the used syringe and thank her, in front of the horrified gaze of an elderly woman.
At the time junkies were still perceived in popular culture as much older, wilder characters, such as those depicted in Dennis Hopper's Easy Rider or in Lou Reed's songs.
None of their companions, two of whom also fatally overdose, are older than 16, as reported by end titles recalling the birth and death dates of the real-life individuals portrayed in the film.