House of Mortal Sin

Father Meldrum is a sexually frustrated priest who has been forced into celibacy by his mother, who pressured him to abandon his wedding plans and enter the church. When Jenny confesses about her abortion and relationship with Terry, Meldrum fixates on her as an object of his pent-up desire. Her disclosure about sexual activity triggers his obsession, and he uses the information from her confession as leverage to control her.

Meldrum gains entry to Jenny's flat on the same night she visits the church for confession. The summary does not specify exactly how he enters, but he appears to use his position as a priest to gain access, possibly claiming pastoral duties. He attacks Jenny's friend Robert, mistaking him for Terry Wyatt, Jenny's boyfriend.

Meldrum mistakenly attacks Robert because he assumes the man in Jenny's flat is Terry Wyatt, her boyfriend who pressured her into the abortion. Robert is merely a friend visiting while Jenny is out, making him an innocent victim of Meldrum's misplaced rage. This mistake sets Robert on a path that eventually leads to his death in the hospital.

Meldrum secretly records Jenny's confession about her abortion and relationship with Terry. He uses this tape as blackmail material to control Jenny, threatening to expose her private confession if she goes to the authorities or reveals his actions. This gives him psychological leverage over her and explains why Jenny is reluctant to immediately report his crimes.

Meldrum kills Terry after Terry confronts him at the presbytery. Terry had learned about Meldrum's actions and threats toward Jenny, so he tracks down the priest to threaten him. Meldrum perceives Terry as a 'sinner' who pressured Jenny into having an abortion, aligning with his twisted sense of divine justice. He bludgeons Terry to death with an incense burner and buries him in a fresh grave in the churchyard.

Meldrum kills Robert in the hospital to eliminate a witness who could identify him. Robert was assaulted by Meldrum and had been unconscious after the attack. By murdering Robert in the hospital, Meldrum removes someone who could potentially link him to the assault and could testify against him if he recovered consciousness.

Meldrum kills his mother Mrs Meldrum after Brabazon urges him to 'complete the pattern' and remove her. Meldrum's mother had forced him to abandon his engagement and enter the priesthood, denying him a normal life and romantic fulfillment. Brabazon convinces him it would be a 'mercy killing' for his frail, bed-bound mother, and Meldrum strangulates her, viewing it as maintaining his sacred life in the church.

Miss Brabazon is Meldrum's housekeeper who has loved him for years. She reveals that Meldrum's mother forced him to abandon their potential marriage and enter the church instead. Brabazon has stayed close to him as his housekeeper, harboring unspoken feelings. After the murders, she consoles Meldrum and they form a suicide pact, showing her deep, twisted devotion to him.

After Vanessa's murder, Brabazon reveals her long-standing love for Meldrum and consoles him. They hatch a suicide pact to 'be together forever' as a final act of commitment. However, when Brabazon actually stabs herself, Meldrum hesitates and does not go through with killing himself. Brabazon dies from her self-inflicted wound while Meldrum remains alive.

Bernard Cutler, the priest who is Jenny's friend, discovers the bodies of Terry and Vanessa and confronts Meldrum. Meldrum tries to deflect blame and claims Brabazon acted out of love for him. He appeals to Bernard's loyalty to the church, asking him to help cover up the crimes 'for the good of the church.' Bernard reluctantly agrees, though the summary does not fully explain his reasoning, possibly fear, shock, or a misguided sense of protecting the church's reputation.

After Bernard leaves, Meldrum makes a silent call to Jenny to check that she is at home. This call demonstrates that his obsession with Jenny persists even after all the murders. He needs to confirm she is still under his control before he disappears. The silence is likely meant to unsettle Jenny, and the audience, showing that the threat has not ended.

After all the murders and Brabazon's death, Meldrum makes a silent phone call to confirm Jenny is home, then dons a cloak and steps out into the night. He disappears into the streets, leaving the consequences of his actions unresolved. The ending is ambiguous, he appears to escape justice, leaving the threat potentially ongoing and contributing to a lingering sense of dread.