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.

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.

Bill joins the military group formed by Ethan, Dominic and Michael. The three men hold a young alien hostage, Isla. Catherine, Sophia and Nathan continue to search for Bill. Adina, and the aliens also set out to find Bill. Chloe accuses the blow when she realizes that Sacha killed Ash. She suggests to her increasingly unstable son to run away with her.

At the university, Sophia watches the videos recorded by Dylan, a young man they found dead, while Catherine focuses on the algorithms he left behind and which decipher the behavior of robots. Thanks to Bill's intervention, Isla manages to flee and join her family.

Threatened with expulsion, Yumyulack and Jesse continue to attend their empty high school after the school year ends. Unaware of the summer break, they believe they are being tested, and attempt to teach each other. They realize their mistake and wreak havoc on the school, and are bribed with straight As after discovering Principal Cooke and Mrs. Frankie having sex in the cafeteria. Korvo and Terry enroll in a junior college, but Terry shoots Korvo with a raygun that makes him dumber. Korvo joins Terry's hard-partying college experience, but accidentally causes the "ice lava" that powers their spaceship to flood the city, freezing everyone in its path.

Bill joins the military group formed by Ethan, Dominic and Michael. The three men hold a young alien hostage, Isla. Catherine, Sophia and Nathan continue to search for Bill. Adina, and the aliens also set out to find Bill. Chloe accuses the blow when she realizes that Sacha killed Ash. She suggests to her increasingly unstable son to run away with her.

At the university, Sophia watches the videos recorded by Dylan, a young man they found dead, while Catherine focuses on the algorithms he left behind and which decipher the behavior of robots. Thanks to Bill's intervention, Isla manages to flee and join her family.

Carlos is determined to solve his father’s murder. Owen is offered a life-changing opportunity. Judd gives into his demons as Tommy begins her treatment.

Judd literally walks straight into the line of fire when an armory catches on fire, sending bullets flying everywhere. Owen questions Judd’s pledge of sobriety. Marjan introduces her boyfriend Joe (guest star John Clarance Stewart) to her visiting parents, Waleed (Michael Benyaer) and Nasreen (Anne Nahabedian), but their dinner doesn’t go as smoothly as she hoped.

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.

After a prominent astrophysicist's body is found in her car, Castle theorizes that she was killed in the vacuum of outer space. As they delve deeper into the case, they find the evidence that keeps pointing them to the impossible - alien abduction.

When the body of a dockworker is found floating in the East River, Castle and Beckett's investigation takes them into the forgotten tunnels of turn-of-the-century New York, where they uncover a secret that's been buried since the days of Prohibition.

Castle and Beckett investigate the murder of a high-class matchmaker. In the meanwhile Castle's novel is being turned into a movie and the Hollywood actress Natalie goes to extremes in the character research, transforming herself into Beckett.

When a family from Maryland is found murdered at their dining room table, the team tracks down other family members and friends to uncover secrets and details from the past in hopes to find out what may have led to it, and to catch who is responsible.

When shooting victims are found in the Los Angeles area with possible links to criminal activity, the BAU searches for a vigilante UnSub.

The BAU searches for a serial killer who leaves distinctive marks on victims' faces with the help of an impressive potential new team member, forensic psychologist Dr. Tara Lewis:

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.

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.

It's Halloween time at The Jeffersonian, as the team gets a surprise visit from newly minted FBI Agent Abbie Mills (guest star Nicole Beharie) and Ichabod Crane (guest star Tom Mison), who have traveled from Sleepy Hollow to claim a headless body already under investigation by Brennan and her team. The new foursome must figure out how to work together to discover who the 200-year-old headless corpse is, and how it is linked to a contemporary murder victim. Meanwhile, Booth and Brennan come up with the ultimate Halloween pranks to play on each other.

A pair of funny sanitation workers (guest stars Sal Vulcano and James Murray; "Impractical Jokers") discover the shredded body of a U.S. Senator in a street sweeper, which leads Brennan, Booth and the team to Capitol Hill, where they meet with U.S. Senator and majority whip Hayley Winters (guest star Brenda Strong) and the victim's chief of staff Eric Morales (guest star Nicholas Gonzalez) to get to the bottom of this political murder. Meanwhile, as Aubrey starts to develop a relationship with squintern Laura (Jessica Warren), he looks into her past to make sure nothing will harm his dream of a future in politics.

The BAU searches for a suspect who controls minds; the hunt puts one team member in danger.

When Kate's niece and her best friend Markayla are kidnapped, the BAU suspects an online predator engaged in sex trafficking who poses as a teenage boy.

When a Los Angeles bus is attacked with sarin gas, the BAU must act quickly to find the suspect before a larger-scale incident occurs.

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.

It's Halloween time at The Jeffersonian, as the team gets a surprise visit from newly minted FBI Agent Abbie Mills (guest star Nicole Beharie) and Ichabod Crane (guest star Tom Mison), who have traveled from Sleepy Hollow to claim a headless body already under investigation by Brennan and her team. The new foursome must figure out how to work together to discover who the 200-year-old headless corpse is, and how it is linked to a contemporary murder victim. Meanwhile, Booth and Brennan come up with the ultimate Halloween pranks to play on each other.

A pair of funny sanitation workers (guest stars Sal Vulcano and James Murray; "Impractical Jokers") discover the shredded body of a U.S. Senator in a street sweeper, which leads Brennan, Booth and the team to Capitol Hill, where they meet with U.S. Senator and majority whip Hayley Winters (guest star Brenda Strong) and the victim's chief of staff Eric Morales (guest star Nicholas Gonzalez) to get to the bottom of this political murder. Meanwhile, as Aubrey starts to develop a relationship with squintern Laura (Jessica Warren), he looks into her past to make sure nothing will harm his dream of a future in politics.

A body is found with a diamond ring in his pocket at a bar. Longworth sifts through the sands of the various characters at the bar, revealing a complicated love triangle.

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

Unsubs from Voit’s network take hostages, torturing and killing them as Voit is confronted by a familiar “face” from his past.

A woman's dismembered body is found on a railway track. Although suicide is suspected, Harrow is not so sure. Meanwhile, the river bones are returned, much to Harrow's dismay, and his troubles are only increased when Dass begins questioning him about Robert Quinn.

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.

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.