In West Germany in the late 1960s, Stefan Brückner Klaus Grünberg finishes his mathematics studies and decides to experience life beyond equations. He hitch-hikes to Paris and soon after, at a bar, he befriends a petty criminal named Charlie Michel Chanderli. Charlie invites him to a party where Stefan becomes introduced to an American girl nicknamed the pussycat—Estelle Miller Mimsy Farmer—and he is instantly drawn to her. Though Charlie warns that she is a drug user and dangerous, Stefan cannot resist the allure and follows Estelle to her hotel room, where she introduces him to marijuana and they share a intimate moment.
Estelle is planning a move to Ibiza and invites Stefan to come along. When he arrives, he discovers she is entangled with a wealthy Spanish ex-Nazi, Dr. Ernesto Wolf [Heinz Engelmann], a revelation that a drug dealer he befriends at a bar hints at rather than explains. Despite the warning, Estelle later brings Stefan into her circle at a hippie party, introducing him to her friends, including Cathy [Louise Wink]. Stefan is captivated by the carefree atmosphere and the sense of escape it offers, and he is drawn to a secluded villa where the pair retreat together. Estelle secretly carries both money and a large stash of heroin she has stolen from Wolf, and Stefan becomes part of a dangerous, intoxicating routine.
The couple enjoys a period of sun, sea, and closeness, but the euphoria is fragile. Estelle introduces Stefan to the heroin, a drug she already knew well, and the line between pleasure and dependence begins to blur. She explains the drug’s nature after a visit from Cathy, making the reality of their situation painfully clear: the drug they’re using is horse—heroin.
What starts as a seductive experiment spirals into a downward trajectory of addiction. Wolf’s demand for the return of the heroin and the money compels Stefan to work in Wolf’s bar in exchange for keeping Estelle by his side, and the dynamic becomes a grim trade-off: Stefan’s labor in the bar in exchange for Estelle’s presence and companionship. One night, Estelle disappears from Stefan’s life, leaving him anxious and unmoored. Charlie returns to press Stefan to abandon the Ibiza world and return to Paris, warning him that Estelle has already ruined two good men and that Stefan risks joining them as a third casualty.
On the eve of his planned departure for Paris, Stefan demands an explanation for Estelle’s recent actions and strikes her in a moment of anger. Estelle, pleading for heroin, reveals that she has been sleeping with Wolf all along; the arrangement she made after her theft forced her into that relationship, and she resents it. After a heated confrontation, Estelle runs away, leaving Stefan in a growing panic. He searches futilely for her and, in a moment of recklessness driven by despair, wounds a worried Charlie who tries to calm him and argue that the pursuit might not be worth it.
The following morning, Stefan returns to the same dealer, begging for two packets of heroin. He uses the drugs despite the dealer’s warnings about their potency and intensity, and he withdraws from life in a final act of desperation. The overdose ends his story with him lying in the open countryside, while Charlie looks on, deeply moved and unable to stop the tragedy from unfolding.
