Flash, Flash. Castle's back and he's being photographed with some super hot, scantily-clad policewomen. We're pretty sure they're not real cops, as this is a promo shoot for the new Nikki Heat book. If you recall, Castle's newest fictional character is based on our favorite homicide detective, Kate Beckett.
Beckett is still plenty peeved at Castle for looking into her mother's murder against her wishes. Captain Montgomery forces her to chat with a reporter who is jazzed to write about her crime-solving partnership with Castle. And when a murder victim is found hanging in a tree, Beckett reluctantly teams with Castle once again.
Lanie's preliminary exam indicates that the victim, John Allen, was dead before being tossed of a roof. Much to Castle's dismay, Beckett suggests he and the reporter head back to the morgue with Lanie. BAM! The medical examiner's van jolts to a stop. A team of masked gunmen storm into the back and steal the dead body. Castle is stunned. Frankly, so are we. What was that about?
With the reporter gone, Beckett tries to get rid of Castle, but he insists he's part of the investigation now. Beckett makes Castle a deal: he can be part of this case as long as he promises to leave her alone afterwards. Castle agrees, although he's sure he can change her mind.
Castle and Beckett visit the victim's wife, trying to understand how a middle-aged insurance actuary and faithful family man could be involved in such a bizarre crime. His widow tells them that the victim had been getting calls from an angry co-worker who had recently been fired. When Beckett has the co-worker brought in for questioning, they discover that John Allen had been lying to his family. He was laid off from his job months ago. Soon after, there's another surprise: John Allen's body is found sliced open with all his organs removed. To paraphrase Castle, "Somebody must have hated this guy's guts."
Lanie finds traces of cocaine inside the victim's body. It seems John Allen was acting as drug mule. His corpse was likely stolen by the folks he was working for. Lanie also notes that John was strangled to death by a killer with a weak finger, as the wounds aren't very severe where the pinky would have been used. Of course, Castle suggests the killer may just be fancy and prefers to stick out his pinky. Like he was having tea!
A fingerprint leads them to the apartment of a paroled ex-con and his cohorts. The men swear that they had nothing to do with killing the victim. They only wanted the drugs inside him. They tell Beckett and Castle it was a client of theirs, Ron Bigby, who put them in touch with the victim. Esposito and Ryan bring in Bigby, who tells them that after losing his job, John Allen ran up significant gambling debts. In particular, he owed a large sum to a tattooed Russian whom he had played in a poker game.
Castle asks regular poker buddies Michael Connelly and Stephen J. Cannell for info on an underground high-stakes poker game. Castle crashes the game and is wired for sound and video. He's given instructions by Beckett to locate the tattooed Russian. After he locates the Russian, the plan is that Castle will leave the club. Think that'll happen?
When Castle gets inside, he sits down at the poker table teeming with tattooed Russians. Looking to flush out the killer, Castle tells the tale of John Allen and how he got involved with the wrong people. Watching from the surveillance van, Beckett sees that Castle has infuriated the real killer. He's the one twisting his prosthetic finger. Realizing that the killer will be going after Castle next, Beckett does a quick change into a hot outfit and works her way inside.
Castle wins the poker game but the killer is upon him before he can cash out. He forces him at gunpoint into the next room. Luckily, Beckett shows up pretending to be Castle's Russian girlfriend. We kinda dig her accent. She manages to disarm the killer and rescue Castle. Afterwards, Castle asks Beckett if she's too scared to look into her mother's case again. Angered, Beckett tells him they had a deal that he would leave her alone and she expects him to honor that. Beckett walks off, with Castle too stunned to follow her.
That night, Alexis arrives home upset. Her boyfriend forgot about their movie date and, even worse, he wouldn't apologize. As he comforts his daughter, Castle realizes his own mistake. He heads back to the precinct and apologizes to Beckett for violating her trust. As Castle walks away, Beckett tells him she'll see him tomorrow. It's just enough to let Castle know they are a team once again.