Tick, Tick, Tick... No, we're not talking about that pulse-pounding "Tick, Tick, Tick..." episode from Season 2. This tick tock is on Beckett's clock. It's counting down to when she and Castle can escape the city for a romantic weekend in the Hamptons. Wonder if they'll be staying near Grayson Manor. Anyway, five on Friday finally rolls around with no pesky murders to spoil the plans. Castle's story is that he's off to write. Ryan and Esposito know that Beckett is also going away with her new boyfriend. They make it their mission to find out just who this mystery man is.
Beckett is in awe of Castle's castle at the beach. She wonders how many other women he's whisked away to this oasis. There have been a few for sure, but none of those other ladies were her. This brings a smile to Beckett's face. Castle is also smiling once he realizes Beckett forgot her bathing suit. Unfortunately, someone else decides to take a dip in the pool as a man covered in blood stumbles in from the beach. SPLASH! The guy's dead in the water. Looks like Castle and Beckett are in for a killer weekend!
The victim is a weekender named Randal Franklin who was at a party up the beach. Local Police Chief John Brady believes his deputy has caught the killer when he wrangles up a drugged out dude who was in possession of the dead man's wallet. Castle doesn't think it's that simple since there's no blood splatter on the alleged shooter. Beckett knows they won't be able to get on with their weekend until he gets some answers.
Castle learns that Franklin was arguing on the beach with a woman in a white dress. The guy was also part of an insider trading scandal. Castle asks for help from Ryan and Esposito, who are busy pestering Lanie about Beckett's boyfriend. The boys question Franklin's wife who says her husband was likely arguing with Natalia Roosevelt, the girlfriend he was ordered to dump. Too bad Natalia is pals with Chief Brady, who arrests Castle and Beckett for interfering in his murder investigation.
Brady learns that Beckett is a top homicide cop, so he asks for help on the case. The guy's in over his head after working in a town where he's never even pulled his gun. Beckett gets Natalia to admit that she thought Franklin was using her to get her council vote for a helicopter pad. She says the victim ran off after getting a text sent from a burner phone. In other news, Castle believes "Caskett" is a cool new "couple nickname" for him and Beckett. Sorry, Ricky boy, we've been using that one for awhile now.
The victim's lungs were full of salt water which indicates he was shot offshore. The drugged out dude remembers seeing a boat owned by Aaron Lerner the night of the murder. He just happens to be one of the people Franklin sent to prison in his insider trading case. Castle trips over a sloppy rope tie job as they confront Lerner at the dock. The guy claims he and Franklin made peace even though there's blood splatter on his boat. Lerner believes the real killer may be Franklin's neighbor, who happens to head a New York crime family.
Castle invites mob man Vinnie "The Scar" Cardono (great name) over to his place for a bite. That was a mistake. He totally ticks off the crime lord who didn't like the fact that Franklin used to buzz his helicopter over his place. But Vinnie the Scar is no killer, at least not in this instance. Back in the city, Esposito and Ryan learn that Franklin was buying buildings to use as meth labs. Beckett and Castle realize that their victim was using his helicopter to transfer drugs to the beach.
Ryan engages in an intense interrogation with Lerner, as he was in cahoots with Franklin. Only some of his questions are about the case. He's more interested in the mystery lady who was with Castle. Lerner's description of her awesome, hot body has Ryan pressing even harder. He's stunned when Lerner blurts that the "hot body" woman is named Kate. Oh boy. Castle and Beckett are both on edge when they learn Aaron Lerner told their colleague "everything." Ryan leaves them wondering just what "everything" means.
Chief Brady believes the marina operator is a local drug dealer who was ticked that Franklin was invading his Hamptons turf. Castle notices a neatly-tied nautical knot at their new suspect's boat. The real killer tied a sloppy knot at Lerner's boat. It becomes apparent that Chief Brady's deputy planted evidence to cover his crime. BANG! Chief Brady shoots the deputy when he tries to take the marina operator hostage. The guy would've gotten away with it if it hadn't been for those meddling weekenders.
Chief Brady promises to keep mum about Castle and Beckett's relationship before leaving them to salvage what's left of their romantic weekend. Back in city, Ryan tells a disappointed Esposito that they should drop the great boyfriend search. Looks like their secret's safe with him, too. As for Castle, he comes up with an idea for a new book called Hamptons Heat. Unfortunately, he won't be able to start it until a negligee-clad Beckett dismounts him. It appears Castle will do anything to get out of writing, won't he?