At the Observatory, Mokrani and Catherine clash over the fate to be reserved for Micah, whom Catherine considers to be a major source of information. Micah reveals to Catherine that she has to find Bill Ward. The latter, for his part, tries to find out more about Emily, still assailed by visions of Adina, the leader of the aliens urging him to kill Bill.

Without telling Emily or her parents anything, Bill decides with Zoe to test on Emily the biological weapon he hopes to be able to use against the aliens. Catherine, for her part, has had difficulty managing her grief since Mokrani's death. She now has only one thing on her mind: to find out who Bill Ward is and find him. Sophia is ready to help him, but Nathan hesitates.

Catherine, Sophia and Nathan make their way to London, accompanied by Victor, a survivor encountered by chance. Along the way, the dangers multiply. Sacha's feelings towards Emily intensify and the young man's behavior becomes more and more disturbing. Feeling threatened, Bill is forced to flee.

M.O.D.O.K., finding himself stifled by GRUMBL’s bureaucratic control of AIM, teams up with Monica to take down their new bosses. Monica's hatred toward M.O.D.O.K. remains, however, and she ends up betraying M.O.D.O.K., causing the two to have a mad scientist duel, which M.O.D.O.K. loses in front of his whole company. Monica is promoted to Scientist Supreme and M.O.D.O.K. is stripped of his authority. Meanwhile, Jodie's life without M.O.D.O.K. flourishes as one of her videos goes viral, launching her into internet fame.

Without telling Emily or her parents anything, Bill decides with Zoe to test on Emily the biological weapon he hopes to be able to use against the aliens. Catherine, for her part, has had difficulty managing her grief since Mokrani's death. She now has only one thing on her mind: to find out who Bill Ward is and find him. Sophia is ready to help him, but Nathan hesitates.

Catherine, Sophia and Nathan make their way to London, accompanied by Victor, a survivor encountered by chance. Along the way, the dangers multiply. Sacha's feelings towards Emily intensify and the young man's behavior becomes more and more disturbing. Feeling threatened, Bill is forced to flee.

When brides-to-be in Savannah are killed on the eve of their nuptials, the BAU suspects a jilted UnSub is at work.

Castle and Beckett find themselves on opposite sides of the case when Castle's old 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.

When three restaurant workers are killed in a robbery/homicide in Las Vegas, N.M., the BAU looks at a cold case that happened in the town six years ago for leads.

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.

Colter and rival rewardist Billie Matalon team up to find a missing high school baseball star.

Owen makes a decision about his future; Tommy receives devastating news; T.K. and Carlos worry about adopting Jonah; Mateo gets his immigration status threatened after an altercation; a doomsday prepper gets trapped in a bomb shelter and The 126 and all of Austin brace for an asteroid crash.

The team investigates the high-stakes murder of a political journalist who was found dead after recently publishing an article exposing corruption in the NSA. Due to the nature of the investigation, Hodgins' paranoia takes over as the team realizes their every move is being watched. Meanwhile, Brennan secretly tries to plan a surprise for Booth and the whole team celebrates Thanksgiving together.

When brides-to-be in Savannah are killed on the eve of their nuptials, the BAU suspects a jilted UnSub is at work.

When three restaurant workers are killed in a robbery/homicide in Las Vegas, N.M., the BAU looks at a cold case that happened in the town six years ago for leads.

Dass and Nichols are closing in on the truth with the discovery of Quinn's car. Meanwhile, Harrow investigates the death of a mother and son in a head-on collision.

Colter and rival rewardist Billie Matalon team up to find a missing high school baseball star.

With time running out, Castle and Beckett must put aside their differences with Agent Fallon (guest star Adrian Pasdar) to avert a city-wide catastrophe.

To solve a murder, Brennan and Booth go undercover at an Old West-style shooting competition, while Angela and Hodgins discuss the future of their family and Cam gets close with photographer Sebastian Kohl (guest star Gil Darnell). Then, the team investigates the murder of a police officer that sends shockwaves through both the Jeffersonian and FBI teams. Behavioral analyst Leslie Green (guest star Sara Rue) is assigned to work with Booth on the investigation and lends her professional assessments on who the cop killer could be, while Cam must make some decisions in her personal life and the entire team re-evaluates what is truly important to them.

When the head writer on one of New York's longest running soap operas is killed with a fire axe, Castle and Beckett quickly discover behind the scenes drama just as scandalous as the fictitious storylines, and most would kill to get ahead.

Owen Strand, the lone survivor of his Manhattan firehouse on 9/11, takes his progressive philosophies of life and firefighting down to Austin, Texas, where he helps the firefighters of Firehouse 126 start anew.

When the BAU investigates incidents of bodies being incorporated into macabre graffiti art in Detroit, they suspect an elusive-yet-notorious street artist could be the UnSub. Also, Dr. Lewis struggles to balance her relationship with her fiancé and her work.

When a woman is murdered in a small town in Florida inhabited entirely by sex offenders, the BAU faces a community full of suspects. Also, Lewis receives a career opportunity that may take her away from the BAU.

Nichol's carries out surveillance on Stephanie after she leaves Quinn a threatening voicemail. Then, after the skull from the river bones body is discovered, a positive identity is finally made. Meanwhile, Harrow investigates the suspicious death of a student from his old high school.

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.

When the head writer on one of New York's longest running soap operas is killed with a fire axe, Castle and Beckett quickly discover behind the scenes drama just as scandalous as the fictitious storylines, and most would kill to get ahead.

With time running out, Castle and Beckett must put aside their differences with Agent Fallon (guest star Adrian Pasdar) to avert a city-wide catastrophe.

Nichol's carries out surveillance on Stephanie after she leaves Quinn a threatening voicemail. Then, after the skull from the river bones body is discovered, a positive identity is finally made. Meanwhile, Harrow investigates the suspicious death of a student from his old high school.

When a skeleton is discovered in a suburban backyard, the home owner becomes the prime murder suspect - until Harrow begins to uncover a tragic secret.

In an attempt to pay off Callan's debt, Fern sells drugs at a devil-themed party. Unfortunately a woman starts to hallucinate and throws herself off a balcony, plunging to her death. Meanwhile, Harrow believes he may be able to break the chain of evidence when Pavich orders the river bones be cremated.

The team investigates the murder of an escape artist whose body is found in the woods. They discover that the victim worked at the Magic Palace, and had some secret activities in the works that might have made him enemies in the magic community. Meanwhile, Brennan and Booth poll their friends as to whether or not the tooth fairy should visit Christine, and Angela continues to work with Sebastian Kohl.