Killer Nun (1979) Timeline Explained – Every Event in Order

Gertrude's drug-induced state clouds her perception of reality. While intoxicated on morphine and heroin, she experiences fragmented, violent fantasies that feel real to her. She genuinely believes she suffocated Jonathan because she cannot distinguish between her drug-fueled nightmares and actual events. The drugs create false memories and guilt, making her accept responsibility for murders she never committed.

Foreshadowing: Earlier scenes show Gertrude reading graphic hagiographies about tortured saints, hinting at her descent into violent fantasy.

• gertrude
• drug addiction
• guilt
• hallucinations
• morphine

Sister Mathieu is the true killer throughout the film. She murders her own grandfather by bludgeoning him with a lamp and defenestrating him to stage a suicide. She then kills patients Jonathan, Janet, and Peter, framing Gertrude by planting evidence like Gertrude's veil near the grandfather's body. Mathieu commits these acts while secretly stealing drugs for Gertrude, creating a perfect cover.

Foreshadowing: Mathieu vows to burn evidence to protect Gertrude immediately after discovering the veil, showing unusual loyalty that masks her guilt.

• sister mathieu
• killer
• murders
• frame

Mathieu was sexually abused as a child by her grandfather, who is also a patient at the hospital. This trauma resurfaces when she sees him in the hospital, triggering her need for revenge. Her killings are rooted in unresolved childhood trauma, and she channels this pain into violence against vulnerable patients, using the chaotic environment to hide her crimes.

Foreshadowing: The film establishes early that Mathieu has an unspoken attraction to Gertrude and appears overly protective of her, hinting at deeper psychological issues.

• sister mathieu
• abuse
• trauma
• grandfather
• revenge

Gertrude exploits her position and increasingly erratic behavior to orchestrate Poirret's termination. As her personality changes due to drug abuse and mental instability, she manipulates situations to turn hospital staff against Poirret. Her growing influence and fabricated complaints about his competence lead to his dismissal, clearing the way for Dr. Roland to arrive and further complicate the hospital's dynamics.

Foreshadowing: Dr. Poirret notes Gertrude's troubling personality change early on, foreshadowing her vindictive actions against him.

• dr poirret
• fired
• gertrude
• manipulation

When Peter tells Gertrude he knows who the real killer is but refuses to reveal details, Gertrude panics and steals his crutches in a desperate attempt to prevent him from leaving or exposing what she believes is her own guilt. This irrational act demonstrates her deteriorating mental state and desperate need to control the narrative around the murders she thinks she committed.

Foreshadowing: Peter's claim that he knows the killer's identity triggers Gertrude's paranoid response, showing how her guilt consumes her judgment.

• peter
• crutches
• gertrude
• desperation

Jonathan, an elderly patient, is actually killed by Sister Mathieu, not Gertrude. During a rainstorm, Gertrude witnesses Jonathan having sex with a young female orderly outside the hospital. That night, Gertrude has a violent nightmare where she suffocates Jonathan, but she cannot determine if the dream was real. The next morning, Jonathan's body is found in the grass, and Gertrude assumes she killed him in her drugged state. Mathieu is the true perpetrator, using the chaos to conceal her crimes.

Foreshadowing: The rainstorm creates an atmosphere of confusion, and Gertrude's nightmare blurs reality with fantasy, making her doubt her own innocence.

• jonathan
• death
• killer
• confusion

Janet becomes another victim of Sister Mathieu's escalating violence. She is bound and gagged, then ritualistically stabbed in the face with needles and slashed across the head and neck with a scalpel. This brutal attack mirrors the graphic hagiographies about tortured saints that Gertrude reads, but it is Mathieu who enacts this violence. The murder is staged to appear as another random killing in the hospital, further incriminating Gertrude.

Foreshadowing: Gertrude's fascination with stories of martyred saints hints at the religious symbolism in the murders, though the killer is not who viewers initially suspect.

• janet
• murder
• brutal
• scalpel

While isolated and detoxing from drugs in her cell, Gertrude's mind clears and she recalls the first murder with accuracy. She remembers that it was actually Sister Mathieu who killed the grandfather - bludgeoning him with a lamp and throwing him from the window. Gertrude realizes she had been misattributing the killings to herself while intoxicated, while Mathieu was the true culprit all along.

Foreshadowing: Mathieu's immediate vow to protect Gertrude and burn evidence after finding the veil suggests she had something to hide from the start.

• revelation
• truth
• memory
• detox

Mathieu confesses to Dr. Roland that she has been stealing morphine and heroin from the hospital to give to Gertrude. She threatens suicide if exposed, using emotional manipulation to control the situation. This confession is strategic - it deepens Roland's sympathy for her and creates another layer of complexity that obscures her role as the actual killer. Her seduction of Roland afterward further complicates the hospital's web of loyalties.

Foreshadowing: Mathieu's confession appears heroic on the surface but serves to redirect suspicion away from herself.

• confession
• drugs
• manipulation
• dr roland

Mathieu's grandfather was the patient who sexually abused her as a child. When she sees him at the hospital, it triggers her traumatic memories and her need for vengeance. She kills him first to settle her personal score, then uses the chaos and Gertrude's drug use as cover for subsequent murders. The killing is staged to look like suicide, but Mathieu plants Gertrude's veil nearby to frame her.

Foreshadowing: Mathieu's intense emotional connection to Gertrude and her willingness to protect her hints at deeper guilt over her own actions.

• grandfather
• first murder
• abuse
• revenge