Arizona tries to reconcile with Callie, who has big news to share; Teddy faces an important decision; the residents receive new interns; the Chief makes an announcement.
Addison starts to have erotic dreams concerning Pete and helps Maya when she comes to her claiming to have gonorrhoea.
The BAU is called upon when bioterrorism is suspected in a series of mysterious deaths and Garcia visits her stepbrother to take care of a difficult family issue.
A female soldier claims to be the victim of sexual assault by her commanding officer, and a college basketball player is accused of accepting a bribe from his university.
When clues in a murder of a young woman implicate Castle and Beckett's nemesis, Dr Kelly Nieman, Castle is called in to consult on the case to help find out what really happened to the woman.