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.

Emily agrees to help Bill test her for the virus, but soon experiences serious side effects. Sacha, who has secretly followed the group to stay close to Emily, tries to remove her from the group. For their part, Catherine, Sophia and Nathan set out again in search of Bill Ward.

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.

M.O.D.O.K. suddenly starts acting like a model employee, dutifully delivering mail and making tablets. Austin has a change of heart and tries to inform M.O.D.O.K. who really is running GRUMBL. Thrown by M.O.D.O.K.’s new behavior, Gary thinks it's Austin's fault, and Monica suspects M.O.D.O.K. is planning something against her. Eventually, M.O.D.O.K. reveals that he is selling his shares in AIM to Tony Stark and starts a new business with Monica. Austin misses the chance to tell M.O.D.O.K. the truth about GRUMBL.

When astrophysicists detect a transmission from another galaxy, it is definitive proof of intelligent extra-terrestrial life. The world's population waits for further contact with baited breath. They do not have to wait long. Within days, mankind is all but wiped out; just pockets of humanity are left in an eerily deserted world.

After the devastating alien attack, disparate pockets of survivors emerge into a shattered world. They quickly realise they must put their differences aside if they are to stand any chance of survival.

TK gets a huge surprise on his 30th birthday when his stepdad Enzo (guest star Henry Ian Cusick) arrives in Austin along with TK’s young half-brother Jonah; Owen’s resentment of Enzo turns physical; Tommy is determined to push through her latest crisis; Wyatt attempts to talk-down a suicidal caller and the 126 must perform a dangerous surgery in the field after a man is impaled in a tree.

A gang killing leads Carlos to new information on his father’s murder. TK contemplates a major life decision as Owen is determined to get Austin’s first responders’ health care coverages increased.

When a famous psychic is murdered, Beckett and Castle search for her killer while also debating on the existence of extrasensory abilities. Especially when a letter arrives from the victim, penned the day she was killed and predicting her own death.

When a coded document hidden by a murdered bail bondsman gets Castle's imagination running wild, Beckett must steer the case back to the violent felons who populated their victim's world.

Mysteries abound when pallbearers at a funeral lose control of a surprisingly heavy casket only to have a second unknown woman tumble out along with the original deceased.

Responding to an "Officer Down" emergency call, Castle and Beckett's latest case takes a shocking turn when it's revealed that the victim isn't a cop but a male stripper dressed up as one.

When two guards at a privatized maximum security prison in Texas are murdered, the BAU suspects that more than one UnSub within the prison could be at work.

When the wife of an increasingly prominent Congressman disappears, the BAU investigate and come to consider his adversaries and political enemies as potential suspects of the abduction, or possibly murder.

Castle and Beckett investigate what appears to be the assassination of an intelligence operative. Meanwhile, Beckett continues her romance with Demming, jeopardizing her relationship with Castle. Forcing them to finally face down their feelings for each other.

When a famous psychic is murdered, Beckett and Castle search for her killer while also debating on the existence of extrasensory abilities. Especially when a letter arrives from the victim, penned the day she was killed and predicting her own death.

Castle and Beckett look into the murder of a young mathematician gunned down with a 200-year-old bullet, sparking some wild theories by Castle about a time-travelling killer.

Another layer is added to the mystery of Booth's whereabouts and the state of his physical condition when the team discovers that FBI Agent Miller (guest star Kim Raver) has not been entirely truthful with the FBI and the Jeffersonian, keeping vital information from them that could lead them to Booth. Meanwhile, the Jeffersonian gets a surprise visitor, FBI digital forensic scientist Dr. Benjamin Metzger (guest star Josh Casaubon), who works with Angela to try to decode the information the team has been able to uncover regarding Booth's location and the circumstances surrounding his disappearance. Also, Arastoo makes a major decision that affects his and Cam's personal and professional relationship.

On Brennan and Booth's first official day back at their respective positions at the Jeffersonian and the FBI, things get exciting when remains are found at a fish farm under suspicious conditions, prompting them to investigate. After it's discovered that someone harvested several of the victim's internal organs before he was dumped in the water, Angela tracks down the seller and buyer of the organs to try to uncover important details in the case. Meanwhile, Booth readjusts to his position back at the FBI and discovers Aubrey has taken over his old office; Hodgins pushes Angela to showcase her photography work; and Cam struggles with her decision to choose work over her relationship with Arastoo.

When remains of real estate agent Justin Ross are found in the forest and appear to have been destroyed by coyote-wolf hybrids, Brennan enlists the help of fellow brilliant forensic anthropologist Dr. Beth Mayer (guest star Betty White) to assist in the investigation. In addition to her professional achievements, Mayer is surprisingly knowledgeable about the world of fantasy football, a key link to Ross' past and one that could provide vital information in finding his killer. As Booth and Aubrey dig into Ross' fantasy football league history, they discover he was actively involved in a Twitter feud with NFL star Lou Divers (guest star Ronde Barber), and was also owed a large sum of money from the league's commissioner, making each of them suspects. Meanwhile, Brennan resists feeling competitive as Mayer impresses the team with her expertise and decades of accomplishments.

The BAU is called to Wisconsin in search of a serial killer, and the team looks for a connection among the victims for clues to the UnSub. Also, Kate has trouble dealing with her niece, Meg, when she begins acting out.

When an innocent family of four is abducted while vacationing in Barbados, Hotch and Cruz enlist the assistance of the FBI's most elite team in handling international cases. They realize that this situation closely resembles a case that the BAU once handled in Florida.

Dr. Daniel Harrow investigates the apparent suicide of a young woman whose grieving father suspects she was murdered.

While stalling the river bones investigation, Harrow digs into the case of a woman murdered with a crossbow, coming dangerously close to a thrill-kill murderer.

Wish enlists R.J.'s help on a bizarre case when his late cellmate's son is wrongly accused of murder.

A gang killing leads Carlos to new information on his father’s murder. TK contemplates a major life decision as Owen is determined to get Austin’s first responders’ health care coverages increased.

A robbery-homicide prompts Beckett to invite Det.Demming to assist on the case; the investigation becomes a competition for Beckett's attention, since both men race to solve the case.

When Beckett and her team burst into a shadowy apartment on the trail of a murderer, the last thing they expect to see is Castle standing over a dead woman's body holding a gun! As Castle protests his innocence, Beckett has to arrest him

When a coded document hidden by a murdered bail bondsman gets Castle's imagination running wild, Beckett must steer the case back to the violent felons who populated their victim's world.

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.

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.

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.

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.

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