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.
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.
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.
When a body of a murdered marine is found in the forest, the investigation leads to the local militia and a weapon deal gone wrong.
Wayne and Roland revisit discrepancies in the Purcell case that have been hidden or forgotten over the years. Among those being reevaluated is Tom Purcell, as well as Lucy Purcell's cousin Dan O'Brien. The glitter of Amelia's book release is tarnished by a voice from the past.
