The BAU team heads to Yakima, Wash., after the remains of a dozen people are found along a creek bed.

The 118 race to the rescue when a structure collapse at a “happiness convention” traps people under rubble. While on FaceTime with her mom, Athena’s father suffers a stroke and crashes through the wall of his house. Hen stretches herself too thin with test prep and her new responsibilities at the 118, while Maddie tries to help new recruit get his bearings at the call center.

With Adina's plan in motion, the world's last hope is for Bill to make one more journey, risking his own life in search of Catherine's help.

One year after escaping the destruction of their planet Shlorp and crashing on Earth, aliens Korvo, Terry, and their child-replicants Yumyulack and Jesse adjust to their new lives. Korvo is determined to repair their spaceship, but Terry introduces him to the television show Funbucket. Realizing that the titular alien is fictional, they create a real Funbucket, who tires of them and befriends humans Travis and Avery. Forced to attend high school, Yumyulack and Jesse are menaced by their classmates and faculty. They shrink a bully named Lydia, hoping to use her to study human behavior. As the Shlorpian family have dinner together, it is revealed that their pet, the Pupa, will one day evolve and destroy Earth to terraform a new Shlorp.

Korvo and Terry place nanobots in the city's water supply to spy on their neighbors. Learning they are not well-liked, Korvo and Terry use the information from the nanobots to win over the community, and run for president of their homeowner association. The nanobots form a sentient person that runs for president as well, and all three expose embarrassing secrets about their neighbors, who break out in violence. The incumbent president Ruth restores order and turns the crowd against Korvo, Terry, and the nanobot person, who escapes from Korvo. Jesse – concerned that Yumyulack is shrinking and capturing too many humans – uses technology to manipulate people who were mean to Yumyulack, hoping to teach him that humans are generally kind.

With Adina's plan for world destruction reaching completion, and our heroes in the alternate world under attack, both sides must make great sacrifices if they are to save humanity.

With Adina's plan in motion, the world's last hope is for Bill to make one more journey, risking his own life in search of Catherine's help.

The BAU investigates if bullying may be the link between two high school students who are the sole survivors after both of their families are killed.

In the first of a two-episode story arc, Castle & Beckett begin a murder investigation that also exposes a plot to kidnap the daughter of a wealthy Middle Eastern businessman.

When three children disappear while riding their bikes on the same path as a similar unsolved disappearance 30 years ago, the BAU team comes in to investigate.

In the powerful conclusion of a two-episode story arc, when the FBI fails to get his daughter back, Castle takes matters into his own hands, reaching out to a shadowy fixer to help him recover Alexis.

After The Disciple comes after two members of the team, the BAU races to help them.

When a blimp suffers mechanical failure and its engine catches fire, Athena and the 118 must rescue victims both inside and outside a packed sports stadium. Bobby and Athena drop off May on her first day of college and discuss honeymoon plans, while Maddie and Chimney go to couple’s therapy.

Booth and Brennan are called to investigate decomposed remains found at the Jersey Shore. The team grows fond of Booth's girlfriend, Hannah, and Angela tries to keep her pregnancy a secret.

The BAU investigates if bullying may be the link between two high school students who are the sole survivors after both of their families are killed.

When three children disappear while riding their bikes on the same path as a similar unsolved disappearance 30 years ago, the BAU team comes in to investigate.

Harrow is desperate to prove once and for all that Francis Chester is alive and trying to kill him, but with no proof, even his most-trusted friends and colleagues doubt Harrow's state of mind.

After The Disciple comes after two members of the team, the BAU races to help them.

The 118 race to the rescue when a structure collapse at a “happiness convention” traps people under rubble. While on FaceTime with her mom, Athena’s father suffers a stroke and crashes through the wall of his house. Hen stretches herself too thin with test prep and her new responsibilities at the 118, while Maddie tries to help new recruit get his bearings at the call center.

When a young woman appears to have literally been scared to death three days after watching a 'haunted' DVD, Castle and Beckett delve into one of their creepiest cases yet.

A skull and decomposing hands are found in a dumpster, and the victim turns out to be a bounty hunter in search of Charles Braverman, a man indicted for the murder of a co-worker; meanwhile, Brennan is asked by Professor Bunsen Jude, "The Science Dude," if he can shoot an episode of his children's show from the Jeffersonian, with Brennan as his special guest.

When a man is found dead in an industrial cake mixer, Castle and Beckett trace the murder to an Irish gang in Staten Island and a beautiful bar owner named Siobhan O'Doul.

Brother arrives in town, knowing everything about her and her family, and she is unable to make contact with her real sibling.

The BAU team heads to Yakima, Wash., after the remains of a dozen people are found along a creek bed.

In a thrilling climax, Harrow comes face-to-face with his greatest fears as Chester initiates the endgame.

R.J. helps a young woman uncover the truth behind her boyfriend's sudden death; a dangerous figure from R.J.'s past resurfaces, bent on revenge.

After The Disciple comes after two members of the team, the BAU races to help them.

When a young woman appears to have literally been scared to death three days after watching a 'haunted' DVD, Castle and Beckett delve into one of their creepiest cases yet.

In a thrilling climax, Harrow comes face-to-face with his greatest fears as Chester initiates the endgame.

After the skull of a promising young dancer is found lodged in concrete at a construction site, the team must first figure out what happened to the victim’s skeletal structure. After learning the victim quit ballet to pursue hip hop, Booth and Brennan uncover another layer of evidence that points them to a suspect who had a secret relationship with the victim. Meanwhile, when Hannah (guest star Katheryn Winnick) is put on assignment in a dodgy part of town, her safety is jeopardized and her life is put in critical danger.

As Rossi conducts a profiling course on his birthday, he receives a call from his serial killer nemesis, Tommy Yates, telling him the location of his latest victim.

The 118 race to the rescue when a birdwatcher is trapped under a tree. Chimney is in for a wild ride when he tends to a drunk driver; Maddie helps a mother and her young daughter when an abusive father shows up at the their house; Eddie catches Christopher in a lie; Buck begins a year of “yes to possibilities” and immediately receives an interesting proposal from a former roommate.

When Castle and Beckett find giant footprints at the site of a vicious murder, the team is forced to confront the unlikely theory that Bigfoot is the killer.

The BAU team investigates a series of home invasions in upscale neighborhoods in San Diego involving casualties.