Mark has reason to celebrate Nurse Mary Capshaw, as she is to become the fundraising director for Community General's Children's Clinic. However, at the dedication ceremony, Capshaw notices a woman from her past, Kirsten Foxx.
Foxx is better known to Los Angeles as the "Malibu Madam", mostly because she was recently arrested for running a brothel with the city's elites as the clientele. In order to afford the attorneys that could keep her out of prison, she has written a tell-all book that names names, and unfortunately for Mary, she's one of them.
Suffice to say, Mary does not appreciate this, even confronting Kirsten at her mansion. This leaves her in perfect position to be in hot water when Kirsten is found murdered and her manuscript stolen. Her seeming hope in A-list lawyer Darren Worthy coming to her defense is for naught, considering he's the killer and not only using her decision as her lawyer to frame her for the murder, but also has plans to boost his career with the help of Kirsten's manuscript.
"In Defense of Murder" displays symptoms of the following tropes:
- Amoral Attorney: Darren's use of murder and blackmail would definitely qualify him.
- And Starring: David Dukes.note
- Asshole Victim: Downplayed examples.
- Kirsten is effectively leaving a woman she considered a friend out to dry to save her own neck at the cost of Mary's clean reputation, and effectively dumped her in an ER and ran when Mary came down with a bronchial infection, but she doesn't feel particularly great about it.
- Also with Judge Shepherd. He cheated on his wife (who had recently come down with pneumonia) with prostitutes that were underage, but a slimeball like Darren doesn't have much more room to judge.
- Blackmail Backfire: Darren attempts to get Judge Shepherd to declare Mary incompetent so she'll be locked away in a mental institution by threat of revealing that he was one of Kirsten's clients, with some of the girls he was serviced by being underage at the time. Shepherd agrees, but when Darren admits he'll be holding onto the manuscript in case he needs another "favor", the judge kills himself.
- Bludgeoned to Death: Kirsten was killed by blows to the head with a glass ashtray.
- Bluffing the Murderer: Mark and Steve bust Darren by getting the building to evacuate via a bomb threat. While everyone else naturally evacuates, Darren slips into the parking garage and climbs some structure to reach the manuscript he stashed there. When Mark, Steve, and other cops find him with the manuscript, complete with Kirsten's blood, it's all over for the lawyer to the stars.
- Driven to Suicide: Judge Shepherd opts to kill himself rather than risk Darren's revealing info leaking and hurting his family.
- Frame-Up: Darren takes on Mary's case primarily to set her up for the crime.
- Freeze-Frame Bonus: The remaining parts of the newspaper article talking about Kirsten's arrest is recycled news about the rapist cops that started Lynn Conklin's killings.
- Macguffin: Kirsten's handwritten manuscript.
- Orgy of Evidence: Darren leaves all sorts of clues to clearly set Mary up. Most glaring in samples of her hair and a piece of a charm bracelet he leaves close to the body (which he plants in a spot Mark saw clearly didn't have them before Darren showed up) and planting the typed manuscript in her fireplace, leaving the pages specifically about Mary partially burnt and left in the flue, which comes off to Jesse as pretty damn convenient.
- Plot Allergy: While stealing things and planting things in Mary's apartment to set her up, Darren brushes his wrist against some sunflowers and gets a nasty rash on his wrist that Mark notices. Later, when Steve and Jesse search the apartment, Jesse comes in contact with the sunflowers while keeping them from falling over, he gets the same kind of rash on his wrist, proving to Mark Darren had been there before Steve and Jesse.
- Right for the Wrong Reasons: Darren does have a point when making a scene of the police focusing so hard on Mary being the killer. He knows damn well she's innocent; all he needs to do to find the killer is see his own reflection.
- Shout-Out:
- Mark gets his idea for revealing Darren's guilt from A Scandal In Bohemia, mentioning the story by name.
"I only steal from the best."- When Mark tries to show Darren that Mary couldn't be the killer because Kirsten's door was left ajar while the photos from the paparazzo who tailed Mary clearly show the door slammed closed, Darren responds that Mark's seen too many Perry Mason movies.
- What Happened to the Mouse?: The episode ends on Darren's arrest, so we never find out what became of Mary and if she returned to the Children's Clinic or not.
