Prior to the events of the episode, Anne discovered that Michael had bought plane tickets to France for Therese, a new postulant nun in the convent, leading Anne to believe that Therese was his lover and that Michael was making the same mistake as before. Anne turned heel by planning to kill Therese, doing so to protect Michael (in her mind) from himself. The villainess utilized Therese's smoking habit and the fact that she took sleeping pills to kill her, setting a fire in her room with a cigarette while she was still asleep, being sure to place the cigarette at the foot of her bed so she wouldn't be awoken. She also put chewing gum inside the lock to the door so she could make it appear the door were locked from the inside, later dislodging the gum as Michael and nun Sister Maurguerite rushed to try and save Therese, who had already died of smoke inhalation.
Anne later confessed to murdering Therese in confessional to Michael, claiming she had committed the crime to protect him, driving Michael to attempt to strangle Anne with rosary beads. Anne's use of cigarettes belonging to Sheila Parker led to her and her fiancee, PR firm owner Daryl Dexter, to be suspected, as they were colluding with Anne to claim the spring near their convent had holy healing water (with Anne initially believing it to be true when her cancer went into remission after she bathed in and drank the waters). But ultimately, the gum led to Anne being revealed as Therese's killer, as investigating DI Richard Poole stepped in the gum while at the crime scene.
Richard and Camille Bordey gathered everyone involved in the case at the convent, where he revealed how Anne had committed her murder of Therese and how Michael had been behind the attack on her following Anne's confession. Cornered, the evil Anne confessed to killing Therese, blasting her for (in her mind) seducing Michael and claiming she had killed her to stop Michael from giving in to her temptation and destroying the convent. After her confession, however, Anne was shocked to learn that Therese was not Michael's lover, but rather the daughter he had conceived through his affair with Ginette Pascal, having been placed in an orphanage by Michael after Ginette died in childbirth. Anne broke down upon learning the truth, claiming she would've accepted Therese if she'd known the truth and begging Michael to forgive her. Anne was later placed under arrest for Therese's murder.
- "I can't lie any more, child. Not here. Not before God. It's true. I had to save Father John from himself. That pretty little thing had turned his head. You all saw that, didn't you? If he'd left with her as he planned to, I would have been left alone. God gave me strength while you were at your weakest. (Michael: "But I loved her.") No, not love. Lust! That's all it was! Just as before. The only real love is here, the family. (Michael: "She was family.") She was a devil! (Sister Anne's confession to Therese's murder)