A woman is discovered stuffed inside a safe on the Upper East Side.
Castle and Beckett meet Ryan at the Upper East Side apartment and learn that there was no sign of forced entry -- just like the three previous home invasions. According to Lanie, the victim, Susan Delgado, received a close range gunshot wound before she was put in the safe. The thieves removed her wedding ring, as well as her finger, using a bolt cutter.
At the precinct, the cops try to connect the four recent home invasions -- each occurred in different high-end neighborhoods, targeting wall safes and expensive jewelry. The thieves have been speeding up their timetable... and are becoming more violent. This is their second murder. Looking over the facts of all the cases, Castle believes the home invaders must somehow know their victims.
They interview Susan Delgado's daughter, Joanne. She's not familiar with any of the other victims nor can she think of any suspicious friends or acquaintances. When she learns that her mother's murder was the fourth such event, Joanne becomes hysterical. Beckett, also having lost her mother to a violent crime, calms her down. She promises Joanne they'll catch the murderers.
Later, Castle wonders out loud what Alexis would do if he were to die. Beckett figures he's trying to get her to talk about her mother's death, but she won't bite.
In the bullpen, Esposito and Ryan update Montgomery. The victims did not know each other. However, according to the forensics report, they found brass shavings in the lock mechanism on the front door of Delgado's house -- meaning someone used a bump key to break in. Esposito once busted a guy who specializes in bump keys -- Evan Mitchell. And, lo and behold, Mitchell was released from jail two weeks before the first heist took place.
They grab Mitchell and find a pistol in his waistband with the serial numbers filed off. Mitchell claims he was at a bar the night before, drinking with his pals. And he's got thirty witnesses to back him up.
Afterwards, Beckett learns that the ballistics from Mitchell's gun don't match the bullet that killed Mrs. Delgado. Furthermore, Mitchell was being arraigned on an unrelated burglary charge the same day the thieves first struck. He's not their guy.
Beckett heads to the firing range to decompress. Castle shows up, offers words of support and asks to borrow the insurance photos of the stolen jewels. He also learns some shooting tips from Beckett, but he's terrible. She makes him a deal --she'll let him borrow the photos if he can hit the center ring in any of his next few shots. Castle smiles and nails all his shots.
At home, Castle pores over the photos of the jewels and realizes the stuff is so high-end, you couldn't use a normal fence to pawn it. You'd want someone with impeccable taste and connections to top buyers. Martha surmises that Castle wants to ask his old buddy Caine Powell, the model for the jewel thief in his book Storm Rising, about the goods. Unfortunately, they haven't spoke since Castle blew Powell's cover by thanking him on the acknowledgements page.
Nevertheless, Castle pays a visit to his old source's home-- where he discovers a state-of-the-art workbench filled with enormous gems, uncut diamonds and even a few showpieces. Powell also has news clippings of big jewelry heists, including the latest string of home invasions. Castle starts to wonder if Powell is the thief when the man, graying but still dangerous, emerges from the shadows and punches him out.
When Castle comes to, Powell offers him a glass of wine and claims all is forgiven -- by the time his cover was blown, Powell was ready to retire. On seeing the insurance photos, Powell declares the jewelry the kind one dusts off only for special occasions, and he deduces that the thieves probably knew about the goods by moving "among their victims." But Powell says he'll need to visit the crime scene for any further insights.
The two slip into Susan Delgado's apartment so Powell can try to glean more info about the thieves. But Powell is stunned by the trail of blood heading to the safe. Thieves in his day had a code of conduct, not like these "gentlemen." Powell hears a noise and motions for Castle to turn off his flashlight. The door opens and Beckett comes in with her gun drawn. Castle stands there, hands raised... but Powell is nowhere to be found.
Back at the precinct, Beckett lectures Castle about disturbing her crime scene. Unperturbed, Castle asks to speak alone with Evan Mitchell. Powell's comment about a code of conduct and how he often ran into other thieves during break-ins makes Castle think Mitchell might know more than he's saying. Under the guise of seeking information for his latest book, Castle gets Mitchell to admit he met one of the thieves, a "shot-caller" who bragged he had "eyes inside" high society. Mitchell then provides Castle with a description.
Beckett and Castle present Joanne Delgado with a sketch of this shot-caller. She doesn't recognize him. Neither, unfortunately, did the families of the other victims. Joanne does reveal, however, that her mother only wore her jewelry for special occasions, such as fundraisers, environmental causes, and so on.
Back at the precinct, the cops write out the names of charitable organizations below a list of the victims' names, looking for an organization common to all four victims. Castle spots it: M.A.D.T. -- the Metropolitan American Dance Theater.
At a ballroom being readied for a M.A.D.T. event, Castle and Beckett interview Anne Greene, the company's director. Greene assures them her employees go through extensive background checks. Nevertheless, she agrees to provide a list of all employees who have access to donor records. She's not as forthcoming, however, about her donors, as most cherish their anonymity. To get that list, Castle and Beckett will need a court order.
At the precinct, Beckett types up a court order. A dubious Castle asks if she noticed how M.A.D.T.'s board members consist of half the judges in town. Fortunately, Castle has tickets to their upcoming fundraiser. They don't have to ask who the donors are because they'll all be there.
Lanie helps Beckett dress for the ball. Nothing seems right. As Beckett starts complaining that the event is just to humiliate her, a package arrives from Castle. The plain gift card simply reads: Bibbitty-Bobbity Boo! Beckett opens the box and finds a gorgeous dress.
At Castle's apartment, Beckett shows up in her beautiful new dress and Martha is suitably impressed. She dashes off and presents Beckett with an expensive necklace to complement the dress.
Outside the event, Castle and Beckett make a splashy entrance on the red carpet. Dozens of people stare as Castle ushers Beckett into his glamorous world.
At the gala, Castle meets Rachel Maddox, the charity's Head of Development, and her boyfriend, Paul. Rachel surprises Castle by asking about Alexis -- she explains that they try to know as much as possible about their donors so they can match their interests with the appropriate programs.
Castle heads over to Beckett to share this discovery and takes her out on the dance floor, claiming it's the only place where they won't be overhead. Castle then sees Powell chatting up Anne Greene. Castle heads over up and accuses Powell and Greene of being the home invaders. But it turns out the only thing they're guilty of is inviting Martha to start the auction. As Martha auctions off a first edition and a date with Castle, he turns away in shock -- only to spy Paul, Rachel Maddox' boyfriend, taking pictures of the bejeweled crowd.
After a background check turns up a long list of felonies, Castle and Beckett arrest Paul. During his interrogation, Paul confesses that he was working for Karl Nadir, a violent criminal he befriended at Green Haven Prison. After they both got out, Nadir found Paul and, threatening violence against Rachel, forced Paul to help him rob the rich.
Off Paul's tip, Beckett, Ryan and Esposito head for Nadir's apartment, while Castle is forced to stay in the car outside. The cops storm into Nadir's one-bedroom apartment, where they find incriminating gear. Unfortunately, the only sign of the perp is a warm coffee mug. As Beckett steps into the apartment hallway, she spots Nadir running away and chases after him.
Outside, Castle waits impatiently in Beckett's unmarked car when Nadir's body lands on the hood! Nadir's face matches the police sketch, which happens to be on the dashboard. Castle and Nadir wrestle, and Nadir punches Castle in the face. Then, just as Nadir is reaching for his gun, Beckett steps on his grasping hand, her gun pointed at his head.
The next morning, Beckett meets with Joanne and returns one of the stolen items -- a locket containing a photo of Joanne and her mother. Beckett also extends an offer to talk anytime.
Afterwards, Beckett stops by the loft to return Martha's necklace, only to find Castle making eggs for Alexis and Martha. Castle pulls up a chair and insists Beckett stay for breakfast. She did save his life after all. And, Martha notes, they've only heard Castle's side of the story. Beckett smiles at this. She takes a seat and begins to tell about the night before.