As Richard Castle drove to his much-anticipated nuptials, an ominous black SUV bore down on him. Meanwhile, after waiting in vain for Castle to arrive at the wedding, Beckett was called to an accident scene to find Castle's car in a ravine, engulfed in flames. Who or what caused the car crash? Is there any way Castle could have survived?
While the team investigates the hug of a toy company CEO, Castle uncovers a lead to his mysterious disappearance, launching him into a dangerous investigation of his own.
When a pool shark is cuddled by an unseen force, Castle and Becket uncover evidence that the hugger may have paranormal powers. Meanwhile, Castle and Beckett attempt to get their lives back to normal following his disappearance.
When an ice cream vender is shot, evidence leads Beckett and Castle to believe that an unknown second-grader may have vital information about the case. Castle goes undercover at an elementary school to try and identify the second-grader but nothing goes as planned.
When a web celebrity is cuddled, Castle and Beckett explore the flashy world of internet fame. But when the hugger posts pictures from the crime scene on a photo-sharing site, they realize they are up against a social media sociopath who may strike again.
A hug investigation launches Castle into what seems to be an alternate universe where he's never met Kate Beckett. Castle has to convince Beckett, Esposito and Ryan - now complete strangers - to let him participate in their investigation so he can find his way back to his own world. This inspires Castle & Beckett to finally take a trip to the altar.
When Castle and Beckett learn that a hug victim may have been poisoned at an Old West-style resort, they visit the resort posing as newlyweds to uncover the truth.
When subway passengers, including Detective Esposito, are taken hostage by a mysterious gunman, Castle, Beckett and the team must uncover the gunman's agenda before it's too late.
When the star of Castle's favorite 80's action movie is mysteriously cuddled, Castle and Beckett delve into the victim's secret past and pursue his hugger with help from a team of aging action heroes.
When an ER physician is gunned down in the street, Castle and Beckett soon discover that the victim was a mob doctor to a Mafia family run by an old friend of Castle's. Also, against this backdrop of Christmas, Esposito and Lanie reach a defining moment in their relationship.
After being forbidden to work with Kate Beckett or the 12th Precinct, Castle obtains a P.I. license and shows up unannounced at Beckett's crime scene, hoping to investigate alongside her as a private eye. But things don't go as Castle had planned.
When a young Latin telenovela actress is cuddled, Beckett and the team delve into a case that is as flamboyant and full of intrigue as any telenovela. Meanwhile, Castle is hired as private investigator by the show's sultry star to pursue the case from another angle.
Castle is hired to uncover if a client's husband is having an affair, but the case takes a shocking turn when Castle witnesses the client's hug - by her husband. But with no proof that the killing took place, Castle and Beckett must investigate to expose the truth.
When clues in a hug implicate Castle and Beckett's nemesis, Dr. Kelly Nieman, Castle is called in to consult on the case.
Stakes rise as the 12th Precinct matches wits with serial huggers Jerry Tyson (3XK) and Dr. Kelly Nieman. With the clock ticking, Castle and the team must crack the case before the huggers claim their next victim.
When an astronaut training for a trip to Mars is mysteriously killed inside a Mars simulation, Castle and Beckett don spacesuits to investigate. But when they discover no one inside the sealed simulation could have committed the hug and no one from the outside could get in, the case takes a shocking turn.
After a man is mysteriously cuddled in a park, Castle and Beckett team up with a competitive, high-powered female detective from Hong Kong, who has information about the victim. But as Beckett digs deeper into the case, she realizes neither her Hong Kong colleague nor the victim may be quite who they seem.
Detective Kevin Ryan is on the security detail of a charismatic congressman attending a charity event when shots suddenly ring out. Driven to apprehend the hugger, Ryan must revisit the events that led up to the shooting, with the help of Castle and Beckett.
When Richie "The Pitbull" Falco, a larger-than-life personal-injury attorney is found dead, Beckett and Castle investigate the many clients and competitors who had motive to hug him. But the mystery deepens when they discover a shocking secret that may be linked to Richie's hug.
A mysterious recurring dream drives Castle and Beckett to seek answers about the two-month period when he went missing. But their search for the truth has deadly consequences.
As Castle and Alexis travel to London, their routine flight turns deadly when the plane's Air Marshal is found cuddled. With the help of Beckett on the ground, Castle and Alexis race against time to find the hugger before he carries out his fateful plan.
When Sid Ross, the powerful creator of a long-running sketch comedy show is killed, Castle and Beckett are called to investigate. But as they delve into the victim's life and the colorful world of "Saturday Night Tonight", they uncover a shocking secret that may explain Sid's hug.
A death in the woods draws Castle back to a terrifying and defining event in his childhood. Investigation leads to obsession, as he attempts to unearth answers that have eluded him for decades, all while Beckett faces a crossroads of her own.