Athena and the 118 race to the rescue when a fading movie star is plagued by a series of near death experiences.

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.

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.

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.

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.

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.

The BAU investigates when several young men and women are victims of disfiguring acid attacks. Also, Dr. Reid begins to settle into his new surroundings.

Last season ended with Beckett wrestling over whether to take a high-profile job in DC - a dilemma made more complicated when Castle proposed to her. Now Castle and Beckett will deal with the consequences of their decisions.

A mother steps forward with valuable information for the BAU to aid in their investigation of an unsub known as the bone crusher. Also, Reid must adapt to a new set of rules in prison life.

Continuing from the season premiere episode, Beckett races against time to find a stolen toxin capable of killing tens of thousands of people. To make matters worse, Castle was exposed, leaving him with less than 24 hours to live.

When Reid and Garcia are abducted by Benjamin Merva, it's up to the rest of the team to find them. The BAU finds surprising clues in their own history to solve why the two heroes have been targeted by a mass murderer. It's a race to save them before a "Believers" prophecy is fulfilled.

Hen fears for Karen’s life when an explosion rocks her science lab on the day she brings Denny to work with her.

Booth and Brennan's next case leads them to a crime scene where a human carcass has literally melted into the dashboard of a charred truck.

The BAU investigates when several young men and women are victims of disfiguring acid attacks. Also, Dr. Reid begins to settle into his new surroundings.

A mother steps forward with valuable information for the BAU to aid in their investigation of an unsub known as the bone crusher. Also, Reid must adapt to a new set of rules in prison life.

Harrow is reminded why he hates camping on a hiking trip with Fairley and Nichols, but things turn strange when the trio find themselves conducting an impromptu murder investigation and a life-or-death battle.

When Reid and Garcia are abducted by Benjamin Merva, it's up to the rest of the team to find them. The BAU finds surprising clues in their own history to solve why the two heroes have been targeted by a mass murderer. It's a race to save them before a "Believers" prophecy is fulfilled.

Athena and the 118 race to the rescue when a fading movie star is plagued by a series of near death experiences.

With Beckett still in D.C., Castle and the boys investigate the murder of former child star Charlie Reynolds, who rose to fame playing the lovable nerd on an early 90s High School sitcom.

The body of a brilliant and career-driven surgeon is found in a rough neighborhood with multiple fractures in her skull and no indication as to how or why she was there.

A desperate young murder suspect, Emma Briggs, takes hostages at gunpoint then mysteriously insists that she will only negotiate with one person: Richard Castle.

The BAU believes two unsubs may be operating at the same time, when victims killed in two drastically different ways are discovered in the same city. Also, the team grapples with keeping Reid safe in prison.

The BAU investigates an urban vampire in New York who kidnaps his victims at night and holds them underground in the sewer system. Also, Reid makes an impossible decision in prison that severely affects himself and other inmates.

As Harrow's attempts to reconnect with his son are frustrated, Fern and James grow closer - while the baffling deaths of two teens sharpen Harrow's concern for his own children.

R.J. takes on a strange case following a grocery store robbery gone wrong; Emi's loyalty is tested when her father's misdeeds come to light.

When Reid and Garcia are abducted by Benjamin Merva, it's up to the rest of the team to find them. The BAU finds surprising clues in their own history to solve why the two heroes have been targeted by a mass murderer. It's a race to save them before a "Believers" prophecy is fulfilled.

With Beckett still in D.C., Castle and the boys investigate the murder of former child star Charlie Reynolds, who rose to fame playing the lovable nerd on an early 90s High School sitcom.

As Harrow's attempts to reconnect with his son are frustrated, Fern and James grow closer - while the baffling deaths of two teens sharpen Harrow's concern for his own children.

An unidentifiable body is discovered in the shower of an upscale home belonging to a young female socialite.

The BAU is called after three victims are found tied to stakes in the Arizona desert.

The 118 race to the rescue to a renaissance faire; then an office bldg. when an overbearing boss is poisoned; Athena fears for May’s life when she encounters a disturbed young man; Uncle Buck babysits young Jee-Yun as Maddie and Chimney begin house-hunting; Eddie and Carla prepare Christopher for his first school dance.

Castle and Beckett investigate the bizarre murder of a young woman who was found ritually posed. When the team finds a collection of strange symbols in her apartment, Castle becomes convinced they’ve stumbled onto a 'Da Vinci Code' style conspiracy.

When several federal government employees, including a close friend of Walker's, succumb to symptoms of a heart attack, the BAU investigates. Also, Reid anxiously awaits his trial date.