Trama

Beckett hasn't heard from Castle since he left for the Hamptons months ago to finish writing his second Nikki Heat novel, "Naked Heat." The most Beckett, Ryan and Esposito have seen of Castle is a bookstore standee of him advertising an upcoming book signing. So when Beckett and her team burst into a shadowy apartment on the trail of a murderer, the last thing they expect to see is the real-life Castle standing over a dead woman's body holding a gun. As Castle protests his innocence, Beckett has no choice but to arrest him on suspicion of murder.—ABC Publicity

Chemistry teacher Chloe Whitman was shot and fell from a hotel room window. She had, clutched in her hand, the address of sculptor Maya Santori. When they arrive at her apartment, the door is open and Castle if found with gun in hand next to her dead body. This is the first time they have seen him since he returned from a summer stay at the Hamptons, with his ex and publisher, where he finished his new book. Beckett's team enjoys arresting the 'traitor' but must release him because the gun he had was a different caliber than the murder weapon. Both victims had recently phoned ex-con Todd McCutchins. When Beckett, Ryan, and Esposito get to his apartment, they find, again, that Todd was dead and Castle was already there. Castle and Beckett make a deal that if Castle can find the connection between the three victims first, he can come back. But is he doesn't, he must leave and not come back., But finding the connection between a chemistry teacher, a sculptor, and a vending machine operator, along with Kitty Canary's bizarre nightclub, will be a tough challenge.—KGF Vissers

Castle and Beckett appear to be aiming guns right at each other.

There is a flashback to three days prior, at the precinct where Beckett, Esposito, and Ryan not doing much but are obviously upset that Castle has been in contact since he lest to work on his latest book with his ex-wife and editor in the Hamptons. The team is called in to investigate a murder. The body of a chemistry teacher named Chloe has been found on the sidewalk of her apartment, where she apparently fell out the window after being shot. In her apartment is evidence that she might have been planning to go on a trip. Chloe's boyfriend is questioned but let go as he didn't seem suspicious. An address written on a piece of paper clutched in the victim's hand leads the team to another residence and they find Castle holding a gun and standing over the dead body of a sculptor named Maya.

Beckett arrests Castle, but he insists that he didn't kill Maya. The questioning turns personal with Beckett confronting Castle about why he disappeared and didn't try to contact her over the summer. Tests prove that Castle's gun wasn't the murder weapon so he's free to go. The two women appear to have a connection, or at least tattoos, and taxi receipts lead the team to the home of a vending machine salesman named Todd who is found dead, with Castle standing over the body.

Beckett agrees to let Castle help investigate the case and they make a deal. If Castle figure out the connection between the victims first, then Beckett will allow him to work with the police again. If Beckett figures it out first, then Castle must leave the police consulting business forever. All three victims had the same amount of money deposited into their back accounts, in cash, on the same day. It's clear that they were working together, but what's the missing link?

Beckett and Castle head to a burlesque club to investigate a lead and all three victims were frequent visitors to the club, which is owned by a woman named Kitty Canary and a man named Earl. Kitty explains that Chloe's boyfriend caused some trouble in the club and Maya and Todd had to intervene. The boyfriend is brought in for questioning but he has no recollection of confronting Chloe in the club. A man who was one of Maya's sculpture models is brought in and he claims that the last time they spoke, Maya smelled strangely like chemicals.

Chloe's boyfriend's apartment is searched and the murder weapon is found. He denies knowing how it got there and demands a lawyer. Castle figures out that the three victims were running a counterfeiting operation. Todd could provide a never-ending supply of one dollar bills, Chloe the means to chemically wash the ink off the bills, and Maya the skills to make printing plates in high denominations. Kitty is the one who supplied the ink and, therefore, she must be the murderer, trying to keep the operations all for herself once the rest finished with their contributions.

Kitty and Earl are chased by Beckett and Castle and the scene catches up to the beginning of the episode, with Beckett and Castle aiming their guns at each other. But, actually, they were shooting at Kitty and Earl, each at their respective backs. Castle is back on the team, since he solved the case first, but Beckett appears to have figured out the connection before Castle. She kept quiet to keep Castle from leaving the team.