Private investigator Ray Donovan calls someone at night, telling them to call him back for some urgent information. Just afterwards, a woman with red hair tells him he's been working too hard, murders him, and grabs an X-Ray he's been looking at.
Turns out the person he called is Jesse's friend, Rick Brooks, who is getting married soon. Jesse calls the detective's number, and Steve - who, as a police officer in Homicide, was already there - answers the phone. When Rick looks through the cases Donovan was working on, at Steve's request, he finds his fiancée, Wendy Windsor, listed on a case about the disappearance of Brian Wolford. As if all that wasn't enough of an issue for the wedding, the woman in red hair turns out to be Wendy's mother Catherine, and if she has anything to say about it, Rick will be marrying her daughter over her dead body... or better yet, his.
"A Model Murder" displays symptoms of the following tropes:
- Alliterative Name: Wendy Windsor.
- Ambiguous Syntax: Catherine Windsor, talking about her digital camera's zoom, says it's 20 to 1. Zoom in on a watch, and Mark says "No, it's quarter of 3", the watch indeed showing 2:45.
- Bluffing the Murderer: It would be possible to go through all the X-Rays to find which one is missing, but the time it would take would make it impractical. Instead, they inform Catherine that they will do it, causing her to try and give them the wrong result by moving a different X-Ray to hide the missing one. Mark and Steve see her doing this, and then she is arrested and the body - along with the gun which killed him and had her fingerprints on it - is found.
- Call-Back: Brian's body was found due to checking for damage caused by the earthquake from the episode "Shaker".
- Car Fu: Catherine murdered Wendy's first fiancé by running him down in her Mercedes-Benz.
- Crazy-Prepared: Mark comes up to Catherine's studio with a spray to test her hands for gunpowder residue, and finds that she does. However, Catherine simply tells Mark she was at the shooting range of her gun club that morning, which is confirmed and renders Mark's discovery meaningless.
- Constructive Body Disposal: When Catherine murdered Brian Wolford, she dumped his body in the wet cement of the metro tunnel he was working on alongside the gun she shot him with. The fact that the metro tunnel was being x-rayed would reveal the body sooner or later, and thus the need to take out Donovan.
- Disappeared Dad: Wendy's father abandoned her mother before she was born.
- Fake Alibi: The murderer had Father Bosley call her office at 8:00. That she answered her phone is supposed to be proof she was in her office at that time, but in fact she had her incoming calls forwarded to her cell phone at the time.
- He Knows Too Much: The detective was murdered because he had discovered where Brian's body had been hidden.
- Make It Look Like an Accident: Wendy's first fiancée, Darren Lomax, was killed in a hit-and-run "accident" which was actually murder.
- Mama Bear: In a particularly screwed up way, Catherine murders her daughter's fiancés as a way of protecting her from them leaving her just like her own husband did to her.
- My Beloved Smother: Catherine, having had bad experience with her husband and wanting to avoid Wendy having the same, has actually murdered her two previous fiancées and is going to murder a third.
- Psychological Projection: Catherine seems to believe Wendy's fiancés are just like Wendy's father, set to abandon Wendy like she was.
- Tampering with Food and Drink: Catherine sends a bottle of poisoned red wine to the bride and groom - knowing that the bride is allergic to red wine so she won't drink it. Luckily, Mark is able to prevent him from drinking it.
