A sand-colored landscape. A bead of red rolls like a teardrop... Wait! This is no landscape. It's a body. Something dark and red crashes down onto the body -- rose petals are dropped by a gloved hand and land on naked skin.
Meanwhile, at a crowded Manhattan rooftop party, famous author and infamous playboy Richard Castle celebrates the release of his latest novel, Storm Fall -- the final installment in his best-selling mystery series.
Castle's publisher (and second ex-wife) Gina scolds the author as she is certain he killed the billion-dollar Storm franchise to punish her. She also knows that he's been having writer's block and has been unable to get started on a new book. Gina threatens to demand the return of Castle's advance if he doesn't submit a new manuscript within three weeks. "I already returned that advance," Castle quips, "I spent it divorcing you."
Back at the scene of the crime, Detective Kate Beckett studies the naked, rose-petal-covered corpse of 24-year-old Alison Tisdale. Beckett learns that the victim was a graduate student in Social Work. As there were no signs of struggle, Beckett surmises that Alison knew her assailant. Medical Examiner Lanie Parish reveals that Alison was shot twice in the chest with small caliber bullets. The murder scene gives Beckett an uncanny sense of deja-vu... But why?
Castle approaches his mother Martha and teenage daughter, Alexis. Castle asks Martha if she mentioned his writer's block to Gina. Martha dismisses the allegation, then quickly leaves to chat up a Silver Fox. Castle confides to Alexis that he killed the Storm franchise because the stories had become too predictable, much like these publishing parties. That's when he turns to discover Beckett standing there, flashing her badge at him.
In an interrogation room down at the precinct, Castle tries to flirt with Beckett and fails miserably. When she shows him pictures of the Tisdale murder scene, Castle realizes it matches a scene from one of his books, Flowers For Your Grave, and that the murder of another recent victim, small claims lawyer Marvin Fisk, matches a similar incident from his book Hell Hath No Fury.
Castle returns home to find his mom singing with the silver fox on piano. His daughter Alexis, meanwhile, is trying to study for a test in the kitchen. When Alexis asks about his interrogation, Castle says that someone is killing people like he does in his books, but what he can't figure out is why the killer would emulate his lesser works.
At the precinct, Beckett hands out dog-eared copies of Castle's books, asking Ryan and Esposito to familiarize themselves with the fictional murder scenes. Ryan and Esposito tease Beckett for owning the copies. But Beckett's unflappable and convinced that clues to the next murder can be found somewhere in the pages of Castle's writing.
Becket and some uniformed cops haul in the boxes of Castle's fan mail they got from his publisher. She learns from Esposito that the Tisdale crime scene was negative for DNA and prints, just like the Fisk crime scene. She then sees Castle talking with her boss, Captain Montgomery, and learns that he's offered to assist in the investigation. Much to her chagrin, Montgomery thinks it's a good idea.
Beckett and Castle sift through his fan mail, she wonders why he's there, as it's obvious he doesn't care about the victims or that the murderer is aping his books. Castle claims he's there for the story, because there's always a story. He then "reads" Beckett and spins out her life story -- despite her wealthy upbringing, she became a cop because someone she loved was murdered, and the killer was never caught. "There's always a story," asserts Castle. And that's when Beckett unearths a fan letter covered with disturbing childish pictures of the Tisdale and Fisk murders.
Castle and Beckett discover prints on the letter but the system's backlogged and, apparently, it'll take a week to identify the prints. Castle pulls out his cell phone and calls the mayor, calling in a favor to get their results in an hour. Beckett lectures Castle about protocol as a call comes in -- another similar murder has taken place.
They find a woman face down in a rooftop pool, wearing a yellow evening gown and a tiara. Castle recognizes it as the murder from his Death of a Prom Queen. According to forensic evidence, the victim was killed and posed -- just like the others. Castle points out that the victim's dress is yellow, though in his book, the garment is blue. Beckett gets a call. They got a match for the print -- Kyle Cabot of Brooklyn.
As they pull up to Cabot's apartment, Becket tells Castle to stay in the car. The cops enter Cabot's place and discover creepy drawings and a plethora of Castle's books. In the bedroom, they find a mural of Rick Castle photos, a bloody blouse with two bullet holes and a 22-caliber gun. And in a hallway closet, they discover Kyle Cabot chanting, "Get out of my house, get out of my house!"
At the precinct, Beckett, Castle, and Montgomery watch Kyle rocking and forth in the interrogation room. Apparently, Kyle suffers from pervasive developmental disorder, which can manifest itself in an obsession with a single subject. Additionally, they have evidence connecting him to all three victims -- Tisdale was his social worker and the other two victims were customers at his diner. To everyone else but Castle, it's a seemingly open-and-shut case.
Castle runs the scenario by pals James Patterson and Stephen J. Cannell at their weekly poker game. The writers laugh at the obviousness and insist there must be more -- like a character who thinks the kid's innocent and keeps digging until he finds the truth. Meanwhile, Beckett locates Alison Tisdale's notes on Cabot and discovers that he had been progressing. She begins to have doubts about Cabot's guilt.
The next day, Beckett arrives to find Castle sitting at her desk, perusing her papers. But before she can protest, he hands her a gift-wrapped copy of Storm Fall, followed by a kiss on the cheek. Smiling, she watches him go... until she realizes he stole her case files. Beckett finds Castle at the New York Public Library and arrests him on charges of felony theft and obstruction of justice. Unfazed, Castle points out that the rose petals in the Tisdale murder were the wrong kind -- grandiflora, not hybrid teas -- which means the obsessive Kyle Cabot is innocent.
Castle then surmises that the real killer set Cabot up to take the fall. Because Alison Tisdale was the only victim who had any real knowledge of Kyle's obsessive condition, Castle figures out that she was the intended target. He just has to figure out why. At the precinct, Beckett, going over the evidence again, comes to the same conclusion: Alison Tisdale was the intended victim.
Castle and Beckett interview Alison's father, the multi-millionaire Jonathan Tisdale, in his office. When Castle asks what would happen to Tisdale's money if something were to happen to him, Tisdale says that it would go to his charitable foundation, which is overseen by his son.
On their way out, Castle points out signs that Tisdale is dying of cancer. Beckett agrees and they both head over to interview Tisdale's last remaining heir, his son Harrison. Harrison confirms that his father was dying, but says he had nothing to do with his sister's murder. He tells them he was out of the country during all three murders and pulls out his passport to prove it.
Afterward, Beckett teases Castle that he was wrong about his hunch, but then admits she thinks Harrison is lying. He didn't ask for the dates of the other murders, didn't even check his calendar. Innocent people do not prepare alibis.
Harrison's alibi, however, checks out -- his credit card company confirms he paid for three round-trip tickets on the dates of the three murders. Castle then suggests that Harrison could have used a forged passport to return.
Castle and Beckett obtain a secure a search warrant and try to intercept Harrison before he can get rid of any evidence. Meanwhile, Harrison races home and starts shredding evidence.
Beckett and Castle pull up to the apartment. But as Castle gets out, Beckett handcuffs him to the car. She'll take care of it from here. After she leaves, Castle pulls a handcuff key from his wallet -- but promptly drops it!
As Castle struggles to reach the key, Beckett and company storm Harrison's apartment -- only to find it empty. Castle spots Harrison escaping, uncuffs himself and chases after the suspect.
Beckett follows, only to discover Harrison holding a gun to Castle and using him as a human shield. But Castle not only keeps his cool, he actually manages to figure out the story behind Alison Tisdale's murder: Harrison didn't just kill Alison for money, he also wanted to punish their father for preferring Alison to him. And with that, Castle elbows Harrison and knocks his gun away. Beckett leaps on him and quickly cuffs him, then shoves Castle for being reckless. "The safety was on!," Castle exclaims as Beckett stares at him, amazed. "You could have told me," she replies.
As the cops lead Harrison off, Castle bids farewell to Beckett. There's something between these two, but since the case is over they'll probably never see each other again. And they're both a little sad about that.
Back at home, Castle taps away at his computer. Finally inspired, he's writing again. The next morning, Montgomery tells Beckett that Castle is basing the main character of his next set of novels on her -- and that he's asking to do more research. When a stunned Beckett asks for how long, Montgomery says it's up to him -- and nods over Beckett's shoulder to Castle, now standing in the doorway and grinning. It seems that this partnership won't be ending anytime soon.