Struggling to adjust to having Richard Castle following her for research — and struggling to adjust even more with his annoying habits and tendency to flirt with her — Detective Beckett is assigned the investigation into the murder of a nanny, found beaten to death and stuffed into a clothes dryer in the laundry room of an exclusive apartment building. This sets off a convoluted investigation into her death, and when it's revealed that the victim had sex in the hours before she was killed, it begins to look like Castle's unorthodox and far-fetched narratives might not be far off from the truth...
The Castle episode "Nanny McDead" contains examples of:
- Brutal Honesty: Castle tells a 77-year-old man living in the building where the victim and her killer worked that he's too old to have sex.
- Clingy Jealous Girl: The killer was having an affair with her employer. So was the victim. The killer demanded the victim stop but it got a little heated.
- Early-Installment Weirdness: Castle and Beckett actually bother to scrub up before meeting with Lanie and the body in the lab, with Beckett inferring this is the ugly reality of the job. And yet, it rarely if ever happens again.
- Foreshadowing: Campaign posters for the politician who will wind up dead in "Hell Hath No Fury" and his opponent are dotted around.
- Laser-Guided Karma: Ian Harris was sleeping with his daughter's nanny Chloe. And with another nanny in the building, Sara. Telling Chloe that he loved her and would leave his wife for her. Then Chloe got pregnant. She ends up not only killing Sara by accident, but also stabbing Ian with a kitchen knife a few days later when he admits he won't be leaving his wife. He survives, but will be facing a hefty divorce from his wife.
- MacGuffin: A significant chunk of the plot involves finding the victim's cell phone. It turns up underneath her lover's bed, leading to Castle and Beckett figuring out who the killer is.
- Marry the Nanny: Sara, the titular dead nanny, was suspected of having an affair with her employer. It turned out that she and her fellow nanny Chloe were having affairs with the same man — Chloe's employer.
- Shout-Out: The title is a reference to Nanny McPhee.
- Title Drop: "C'mon — Nanny McDead is found in the spin-dry, you don't think the captain's going to let me in on that story?"
- Yandere: Chloe, the victim's best friend, who killed her because they were both sleeping with Ian, who had gotten Chloe pregnant. When Beckett and Castle approach her in the laundry room, they find her cutting at her own leg with a knife.
