Laura Coover

When clues in a murder implicate Castle and Beckett's nemesis, Dr. Kelly Nieman (guest star Annie Wersching), Castle is called in to consult on the case. But as the team delves deeper into the investigation, they uncover connections to notorious serial killer Jerry Tyson.

As Agent Carter gets closer to Stark's stolen technology, her secret mission could be unraveled by an SSR arrest.

Deputy Director Ochoa volunteers the team to assist with a covert operation aimed at taking down a terrorist group; Callen is concerned about what this kind of assignment may mean for the future of the team.

Mike and Molly are invited to her boss's Halloween party -- a holiday Mike hates.

Molly's disappointment about something at work gets in the way of the holiday spirit.

Mike encourages his mother to get a job, not realizing how it will impact Molly's life.