The Bloodstained Butterfly

In the rain, Françoise Pigaut meets a man in a public park and is attacked. The man gags her and stabs her to death with a switchblade. She tumbles down a hill, and a little girl in a raincoat finds her and rushes to get help.

Marchi is seen fleeing the park and is arrested, taken into custody. The motive is discussed in terms of a rumored past incident involving Françoise. The arrest marks the start of a high-profile trial.

Françoise's death leads to Marchi's conviction, as the motive is presented as her threat to report him. It is implied he killed her to silence the accusation. Court proceedings begin to shape the narrative.

It is revealed that Giulio Cordaro, Marchi's lawyer, deliberately held back a more aggressive defense to protect his affair with Maria. The revelation hints at a compromised defense and a tainted trial. The consequence is that Marchi remains convicted, despite questions about the case.

Giorgio, a young pianist, starts dating Sarah, but remains distant from his family and buries his discontent in drinking. He projects a charming exterior that masks deeper tensions. The relationship introduces a key dynamic later connected to the murders.

The relationship grows strained when Giorgio behaves aggressively toward Sarah during a night together. His temper undercuts his charm and hints at a darker side. The incident foreshadows the unveiling of the killer.

A prostitute is found murdered in the same park, bearing hallmarks similar to Françoise's death. The killings suggest a serial threat operating in the park. Police begin to notice the pattern, though the parallels are not yet fully connected.

A caller claiming to be the killer taunts Inspector Berardi, threatening to kill again. The intimidation heightens the tension around the case. Investigators scramble to decipher the caller's identity and motives.

Shortly after, a third woman is slashed to death in the same park after supervising two children. The spree escalates and deepens the mystery. Public fear grows as investigators chase elusive clues.

Maria returns home to find Giulio attempting to rape Sarah, and she kicks him out of the house. The personal betrayals intersect with the murder investigation, widening the circle of suspect and motive. The domestic upheaval pushes Marchi’s case into a new light.

In a retrial, introducing Marchi's mistress Marta, Marchi is found innocent and released. The reversal exposes weaknesses in the prior proceedings. Doubt about the killer's identity grows.

The inspector visits the store where switchblades were bought, and the owner identifies the killer. The clue narrows the field and points toward the person connected to the park murders. The discovery shifts momentum toward solving the case.

A meeting in an abandoned building reveals Giorgio as the killer and Françoise's lover. He confesses that he killed the last two women, while believing Marchi murdered Françoise. The final pieces of the puzzle start to fit together.

Giorgio shoots Marchi after his confession; Marchi stabs Giorgio as he tries to flee. In a final reversal, Giorgio shoots Marchi dead, dying with a smile at his completed plan. The duel ends the killer's game and confirms Giorgio's role in the murders.