You better watch out! Santa Claus needs to put himself on the naughty list as he speeds down the street (in a car, not a sleigh) firing gunshots at a man on the run. BANG! BANG! The running man is hit. Santa hops out of his hot rod. BANG! One more shot and the victim is dead in a display window. It’s not a very merry way to start the holidays. It does, however, get Beckett’s mind off the Castle family poem she was supposed to write.
The murder victim is an ER doctor named Eric Mercer. A blue backpack he was carrying is missing. Eric was frequenting a mob-owned building in Queens before he was killed. There’s an entire surgical suite set up there. Castle realizes that Eric Mercer was a mob doctor. He was involved with the Carlucci crime family. Castle knows the guy who runs things with them. Dino Scarpella helped him with research on a Derrick Storm novel.
Dino runs things out of a strip club. His Chief of Security is Rocco Carlucci. Christopher Carlucci is his V.P. of Corporate Affairs. Dino claims he has no info that could help. Christopher Carlucci might though. He owns a car that matches the one the killer Kris Kringle was driving. It just happens to have a Santa suit in the trunk. Christopher isn’t talking. However, Dino might be. He asks to meet with Castle. Alone.
Dino says Eric Mercer was family. He looked after him. Christopher is innocent because Dino was with him at the time of the murder. Castle is asked to find the real killer. Dino will vouch for him giving him access to connections no cop could ever hope to have. It’s an offer Castle can’t refuse. Dino makes him take a blood oath. They’re family now.
Christopher said that Eric thought he was being watched. He sent him to a place to pick up some counter-surveillance devices, but Eric was actually looking for stolen credit cards and a possible getaway car. The victim hid his backpack in a salt depot. It holds bloody clothes with bullet holes. They would fit a rival mob family member named Luca Tessaro, who has been missing for three days.
Rocco tells Castle that Luca once tried to have his way with Dino’s daughter, Jane, who may be the killer. Beckett finds blood evidence to suggest this. Castle relays this information to a disappointed mob man. Jane admits that she was at the crime scene, but she didn’t kill him. She was in love with him. Jane says Luca had been shot. She called Eric for help, but it was too late. Dino swears that if the Tessaro family killed Eric, there’s going to be an all-out mob war.
Castle and Beckett discover that Luca Tessaro is alive. Someone new was making a play for control of the neighborhood. Luca was shot by this mystery mafia man. Castle uses a connection to help track down the killer. Surveillance footage captures footage an image of the bad Santa. It turns out to be Detective McBride, the Organized Crime cop who fed info to Beckett at the start of the investigation. Case closed. As for Dino, he lets Castle know that he now owes him a favor.
Lanie ask Esposito to meet the parents. After all, the two of them are engaged. Well, that’s what Lanie told her parents. It was just easier that way. Of course, now they need to keep this little white Christmas lie going. Ryan is more than happy to help by concocting an over-the-top proposal story. All this fake engagement role playing has Lanie and Espo realizing that they are crazy for each other, but not in the same way her parents are. This gives them some clarity about their future together.
Captain Gates reveals that Detective McBride was killed by an unknown assailant while being transferred. The D.A. knows that Castle was working with known members of organized crime during the case. This doesn’t reflect well on him. Gates tells Castle that he is no longer permitted to work with the N.Y.P.D. There is barely time to digest this when Beckett approaches with her draft of her holiday poem. Castle does his best to put on a happy face as she reads it, but inside he knows that Christmas just became a little less merry.