Neal is forced to make a dangerous deal with Matthew Keller’s former adversary in order to save his partner and friend.

Erica, seeking revenge against Anna, heads to Hong Kong to carry out a mission to strike a lethal blow against Anna. Meanwhile, Anna learns that Tyler’s phosphorous level is too low – even after the Red Rain — and he might become useless to her; and Lisa and Diana bond, beginning to form an alliance against Anna.

Castle and Beckett investigate the apparent robbery-homicide of a New York cab driver, only to discover that the victim was involved in a mysterious conspiracy with unimaginable consequences. As the stakes continue to rise, hard-charging federal agent Mark Fallon takes over the investigation. Together, Fallon, Beckett and Castle must race to unmask the truth about the victim before it’s too late.

Marshall becomes obsessed with saving the environment after seeing a documentary on garbage. Ted runs into The Captain. Barney admits he has feelings for a woman.

When a modern-day prospector is found dead near a mining site and Lisbon is injured during the initial stages of the investigation, Agent Hightower joins Patrick Jane in the field for the first time.

Frankie looks for a friend for Brick; Sue sneaks into an R-rated movie against Mike’s wishes; and Axl and his band need a hot female for their music video and try to get stealth footage of their sexy biology teacher.

Castle and Beckett find themselves on opposite sides of the case when Castle’s old school friend emerges as the prime suspect in his own wife’s murder. As they work to solve the crime, Castle comes to realize that one of two terrible things must be true… Either Detective Beckett is about to arrest an innocent man for murder, or his old friend is a cold-blooded killer.

As the story shifts back to life “over there,” the absence of Colonel Broyles changes the dynamic of the Fringe Team as they investigate a bioterrorist armed with an insect that has a taste for human flesh. Meanwhile, alternate Olivia is reunited with her beau, and Walternate remains determined to save his world but discovers there are certain lines he will not cross.

Claire and Phil decide to reprise their role-playing adventure from last year’s Valentine’s Day. Jay’s surprise plans for Gloria keeps getting interrupted. A secret admirer comes between Cameron and Mitchell.

While Alicia races against Louis Canning to round up the most clients for an Erin Brockovich-style class action lawsuit, a mole is detected in LGB law firm, who seems to be working for Louis.