Castle and Beckett's long-awaited wedding is almost here, but when a shocking surprise threatens to ruin the big day, they are sent on a wild mission filled with masked men, angry bikers and a charming ne'er-do-well from Beckett's past.

With their best lead in hand, Castle and Beckett are ready to take on LokSat. But an unforeseen twist puts their case – and their lives – in jeopardy.

Castle and Beckett arrive at a crime scene to discover that the female victim bears a shocking resemblance to Medical Examiner Lanie Parish. As the team tries to make sense of this mystery, they realize the killer may be targeting detectives of the 12th Precinct. Dr. Kelly Nieman, an exclusive Manhattan cosmetic surgeon who draws Castle and Beckett's interest because of her connection to the victim.

Before dying, he hands a mysterious bundle to the priest. When the bundle turns out to be a smiling baby boy, Castle and Beckett find themselves accidental nannies to the newborn. But when they determine the baby and the victim were not related, they discover that finding his rightful parents may be just as hard as solving the murder.

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.

As Castle and Beckett investigate the ritualistic murder of a young woman, they find strange symbols in the victim's apartment; Castle struggles with Alexis' decision to move in with Pi.

When a pop star is found dead in an alley, Beckett and Castle look into her hard-partying lifestyle; a shocking revelation rocks the investigation.

Beckett's side of her abrupt disappearance is revealed. After receiving a mysterious tip from her past, Beckett is launched into a fight for her life, with a team of mercenaries hot on her trail. While Castle investigates why his wife is on the run, Beckett must figure out who wants her dead, before they can finish the job.

When Castle's idol, a famously reclusive author, turns up dead, Castle is determined to solve his hero's murder. But as he and Beckett dig deeper, they discover that truth is stranger than fiction.

When the assistant to Modern Fashion Magazine’s dictatorial editor Matilda King is found murdered, Castle and Beckett are thrust into the glitzy, ruthless world of high fashion in their search for the killer. Meanwhile Beckett’s history in the modelling world gets her access to a very special wedding surprise.

Castle and Beckett delve into the world of extreme sports when a mysterious motorcyclist shoots an up-and-coming professional skateboarder.

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 murder.

When Beau Randolf, the founder of hit adult video franchise "College Girls Gone Crazy," is murdered, Castle and Beckett are confronted with a lengthy list of husbands, fathers and ex-college girls who all have motive. So to find the killer, they must delve deep into the victim’s life, where they find surprises at every turn. Also Alexis starts a video blog, but Castle is not happy that personal and intimate details about her life are being made public.

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. But as they trek into the world of primate research, big game hunting and mythological creatures, they realize that finding the man (or beast) responsible may put them on the endangered species list.

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. But the case takes a turn for the strange when Agents Beckett and McCord arrive from Washington to take over the investigation, creating competitive tension in the precinct. But why would a washed-up actor's death warrant Federal scrutiny? Whatever the reason, Beckett and McCord aren't telling. Meanwhile, Castle has to contend with a new face at the 12th, NYPD Detective Frank "Sully" Sullivan.

When a famed relationship therapist is murdered, it appears that her access to the secrets of her elite and powerful clients led to her death. But when Castle and Beckett discover the victim was in possession of a rare object worth millions of dollars, they realize that this case may be even more complicated – and dangerous – than they thought.

When the body of a local college fraternity student is found gruesomely murdered, Castle has to go undercover as a professor in order to gain access to the victim's world. However, he and Beckett soon discover that behind the fun and games of college are some darker secrets the university wants to keep hidden.

After a movie star turned theater actor is mysteriously killed, Castle and Beckett go backstage and learn the star had more to worry about than just his lines.

A beloved former major league baseball player is found dead after a goodwill trip to Cuba. The investigation, which includes running into Joe Torre, leads the detectives into New York's Cuban community to solve the murder. Meanwhile, Alexis' genealogy project forces Castle to consider the identity of his unknown father.

An "Officer Down" call turns out to be a male stripper dressed like a cop. Castle and Beckett explore the world of male strip clubs and struggling actors, all people in pursuit of fame. They need to determine if the murder was because of the victim's dreams of stardom or something more sinister.

During rehearsal for "Baron's All-American Beauty Pageant," the contestants are shocked to discover the body of Miss Illinois - strangled, but by whom? As Castle and Beckett delve into the cut-throat competition of the pageant world, they learn that a number suspects had motive for murder, including jealous fellow contestants, the pageant's larger-than-life millionaire sponsor, Victor Baron, and the show's host -- hedonistic TV personality, Bobby Stark.

When Odette Morton, a contestant on the hit competition show “A Night Of Dance,” is found murdered in her dressing room, Castle and Beckett must navigate the case’s many twists and twirls without stepping on each other’s toes. But as they delve into Odette’s past, they discover that this reality starlet was harboring a shocking secret that may have led to her death

When an up and coming DJ is killed at a pop star's album release party, Beckett and Castle must dive into the raucous world of New York's music industry. Then, when the investigation leads to a troubled teenager, Esposito takes the kid under his wing, hoping to put him on the right track before it's too late.

Castle and Beckett investigate the murder of a Wall Street trader, but the case takes a shocking turn when the they discover the victim was an undercover informant for the U.S. Attorney’s office. To complicate matters further, the U.S. attorney involved is Elizabeth Weston, Captain Gates’ estranged sister.

When construction workers find the body of an infamous New York mobster who disappeared in the seventies, Beckett and Castle try to solve this three decade-old mob hit. Unfortunately, their only witness is a man who thinks it’s still the 1970’s, so to uncover what he knows, they must play into his delusion, and party like it’s the last days of disco.