Castle and Beckett's first case together is to solve the mystery of the death of a young nanny inside a laundry room; their investigation leads to a twisted world of play dates between babysitters and their employers; Castle considers Beckett's character while continuing to write for his "Nikki Heat" series.
Bobby meets Athena’s parents for the first time and Maddie attempts to end her marriage for good, causing Doug to insinuate himself even deeper into Chimney’s life. Meanwhile, a tanker carrying a tiger shark crashes on the freeway and a gas leak in a plastic surgeon’s office happens mid-surgery.
The BAU is called to Miami to investigate a serial killer who appears to have a conflicted sexual identity. Meanwhile, JJ's secret is revealed.
Vivien and Violet find themselves in a dangerous situation eerily similar to a past event. Ben goes back to Boston to fix a mistake.
The line between the living and the dead blurs on Halloween. Two of the house’s previous residents give the Harmons decorating advice.
