Joannie Timberman is shot at the home of Professor Charles Evans, for whom she worked as an editor. Joannie had recently had an abortion, and Evans admits he was the baby's father. He says that his girlfriend Diane Posner doesn't know about his affair with Joannie. But on the night of the murder, Evans and Posner suddenly cancelled plans to spend the weekend together. Evans went to a conference, and Posner drove to her vacation home. An electronic toll gate shows she drove back a few hours later, and was in Manhattan at the time of the murder. She is arrested when forensic evidence places Joannie in the car.
Evans now says that he told Posner about his affair, and broke up with her. Posner denies this, but witnesses indicate that she's obsessed with Evans; even sending her son Austin to boarding school because Evans didn't get along with him. Subsequently, Posner attempts suicide and leaves a note for Evans, saying she is trying to protect him. When her phone records show she really was at her vacation home at the time of the murder, she says Evans drove out to see her, and she lent him her car. He later told her he'd killed Joannie. Evans is arrested, but then McCoy learns that Posner (who is a lawyer) was reading up on case law about when a prisoner's mail is admissible as evidence. He realizes that she wanted Evans to look guilty to protect someone else - Austin.
In court Austin confesses that he visited his mother, borrowed her car, and drove back to her home. He intended to make her happy by talking Evans into taking her back. Evans wasn't there, but Joannie showed up instead. Austin blamed her for his mother's problems so he killed her in a rage. Although the jury is sympathetic, Austin is convicted of manslaughter and receives ten years in jail. Posner tries to speak to Evans after the verdict but he hastily leaves; Ross surmises that Posner would have just begged him to get back together with her again.
This episode contains examples of:
- Driven to Suicide: Posner attempts suicide in jail.
- It's All About Me: This was very clearly Evans' attitude.
- Off to Boarding School: The trope is referenced with the mention that Austin was sent to boarding school right after Evans moved in with her.
- Murder the Hypotenuse: A varient, as one girlfriend's son murders the other girlfriend on behalf of the mother and without her knowledge.
- Taking the Heat: Posner prefers to be tried and convicted of the murder herself than allow her son to be.
- True Art Is Incomprehensible: Applies to a lot of Evans' works.
- "Well Done, Son" Guy: Austin just wanted Posner to be proud of him, but with Evans around, she didn't seem to care.
