It's a dark and stormy night at a manor, and Ray Hammett walks down the hallway. He enters an office with a corpse lying on the desk, and Nate is seated next to it. Nate says that it isn't what it looks like, but Hammett doesn't believe him and accuses Nate of killing Morris Beck.
Three Days Earlier
Nate and Sophie meets with the new client, lawyer Judy, who explains that building designer Morris Beck is responsible for the collapse of three buildings by cutting corners. There's no chain of responsibility and Judy needs his original blueprints that he kept for certification. Beck got her fired from her law firm and has buried her in motions. She needs the original schematics for her case or it will be dismissed in a week.
Later, Sophie and Nate arrive to see Beck, posing as representatives of Masaari Global. Eliot is working as a janitor in Beck's building. As they arrive at Beck's office, they overhear Beck's daughter Hayley asking Beck's VP of Development, Tom Case, for the loan of a company car after she totaled her own car. Tom tells her to talk to her father at the party. As Hayley leaves, Beck comes out to see him, and tells his assistant Potter to set up the murder-mystery party for the next night.
Nate and Sophie want Beck's company Beckworx to do construction in the desert and remain discrete. Beck already has a quote and Sophie offers to type in her e-mail address to send them. Hardison receives the transmission and creates a skeleton key. He sends it to Parker, and Eliot brings her in via a garbage can. She uses the skeleton key to access Beck's server room and inserts flash drives to copy the blueprints.
Later, the team meets and Hardison reveals that the blueprint files are coded. There are a series of numbers and they discover that they are GPS codes to Beck's manor on an isolated island. Nate figures that Beck keeps the numbers in the system and the blueprints at his manor. There's no way in until Nate remembers that Beck is holding a murder mystery. Hardison can get himself, Parker, and Eliot in, while Sophie and Nate can get in as Beck's guests. Once they get there, Parker can get into the safe, they'll steal the blueprints, and they get out using the guests as cover. Each year Beck humiliates his competitors by inviting them to his manor to compete in a game of some sort, and this year the guests must come as fictional detectives.
The next night, Sophie, dressed as Irene Adler, arrives at the party and chats with Potter briefly. Case interrupts them but spots Hayley and goes to intercept her. Sophie checks in with the others, who aren't happy with the costumes she's chosen for them. The manor has its own power and suffers from occasional blackouts. The team goes to work and Nate and Sophie dance. She comments that he's been edgy since they took the job, and Nate admits that he's getting tired of ultimately accomplishing nothing when there's always another greedy businessman to take down.
A drunken Beck makes his first speech of the night. He insults one of the guests, William, who accuses Beck of rigging the previous year's game. Potter calls the murder mystery to order and collects all of the cell phones so no one can access the Internet and cheat. Beck insists that all of his competitors hate him and dismisses them as plodders. A drunken Beck has Potter take him to get his costume.
Marco Capriotti approaches Sophie and accuses her of stealing union work. He warns her to stay away from Beck because people around him tend to get hurt. Ray Hammett, a Salem police officer, tells Capriotti to take it easy. He then talks to Sophie and explains that Beck's presence and pull with the city fathers earns him police protection. Hammett flirts with Sophie and they dance.
Nate asks for an update from Eliot on their escape plan, but all Eliot has found is an antique motor boat. Hardison checks the power lines and determines that the system is prehistoric with no computers to hack. Nate tells him to focus and Hardison tries to make a pulse map of the systems to find the main control room and the state-of-the-art safe with the blueprints. Meanwhile, Parker walks off distances in the hallway and notices something unusual. Hardison finds a major power juncture and sends Parker to check it out. She goes there and finds Hayley and a young man kissing in the pantry room. Parker tells Hardison, who pinpoints another main power source. Nate tells him that he'll go after it.
A costumed Beck steps out onto the balcony and tells the audience he's going to give them a fair shake. Meanwhile, Nate and Parker both try to go to the juncture box. They argue until Parker finally gives in and steals a bodyguard's hat as a distraction. The lights go out and Nate catches a glimpse of someone struggling with Beck, throwing the businessman over the balcony. When the lights come up, Beck is on the floor, dead. Nate steps out and Hayley yells that he killed her father.
Sophie tries to calm everyone down, but Potter starts to call security. Stalling for time, Sophie tells everyone that the mystery has begun. Potter points out that the intended victim is still alive. However, Sophie claims that Beck's corpse is a dummy and that Beck planned something new and exciting. She tells them that no one is leaving until they solve the mystery. When a doctor offers to check the body, Nate comes down and insists that it's instant disqualification. Case doesn't believe their story, but Sophie says that he's also a contestant and has a chance at the $100,000 prize. Eliot comes in and Nate says that he's the designated crime doctor and will provide them with more clues.
Eliot hauls the body awhile and Nate accompanies him. As Sophie says that anyone could be a suspect, Hammett steps forward and asks if she's a suspect. Sophie flirts with him again and says that there's another dance in it for him if he cooperates. Hammett checks the floor and finds real blood.
Eliot and Nate put Beck's body in the office. Nate assures them that he didn't kill Beck, and Eliot confirms that someone snapped Beck's neck before he hit the ground. After some consideration, Nate puts Sophie on crowd control while Parker and Hardison look for the safe. Eliot disagrees, warning that if they don't solve the murder, Nate will go back to prison.
Hammett comes to the office and Eliot goes out to see him. Sophie steps in and asks Hammett to come with her to help with clues. Eliot goes back into the office and figures that the killer can't get off the island. Meanwhile, Nate reviews what he saw and then asks Eliot to help him find the killer. When Eliot wonders how, Nate sends him down to act as a grifter to spot the killer based on what little he saw. He remembers seeing the killer holding something shiny and tells Eliot to check to see if anyone has something like that in their pocket.
Eliot talks to Capriotti and warns him to stay away from Sophie. When the union leader picks a fight, Eliot knocks him down and confirms that he has a silver flask in his jacket pocket. Nate doesn't think that Capriotti took his problems with Beck personally, and has Eliot look for someone with a personal beef. Eliot considers Case.
Hardison keeps checking his pulse map, while Parker tells him that the dimensions of the house are wrong. She asks Hardison if she should worry about claustrophobia and then slips away when he's not looking. Nate tells Hardison that Eliot will find her while he focuses on the safe.
Hammett tells Sophie that he thinks Beck is really dead. She plays along and the officer insists on finding out what's going on. Hammett tells Sophie to stay close and she agrees.
Eliot sits down with Case and they talk briefly about Beck. As Case goes to get a drink, Eliot trips him and confirms that he has a cell phone on his pocket. Nate remembers that Case was on the floor immediately after the murder and isn't sure if the man could have killed Beck and got there in time.
Hardison runs into a guard and knocks him down. He runs into a dead end and Parker yanks him into a secret passage, which leads to the secret room with the blueprints.
Case talks to Eliot about how he wants Case dead. Nate remembers hearing a ripping noise and tells Eliot to check and see if Case's jacket has any rips. Eliot slams Case's head into the bar and knocks him out, and then confirms that there are no rips in the man's jacket.
Parker and Hardison leave the secret passage and inform everyone that they have the blueprints. Eliot warns them that Nate is still the likely suspect in Beck's murder. Nate takes out his earbud and then goes to the window of the office.
Hammett gets Sophie alone and accuses her of lying the entire time. He figures that she's in on whatever is going on, and explains that he took a photo of Nate and sent it to Interpol. They confirmed that Nate is a grifter and thief. Sophie denies everything but Hammett wants to know why she's keeping him away from Beck's body. He handcuffs her to a chair when she tries to flirt with him, draws a gun, and goes to deal with her partners. Sophie tries to warn Nate but gets no response.
Nate remembers more of the murder and how the power went out before the thunder crashed. He puts his earbud back in and tells them who killed Morris Beck. Hammett storms in and accuses Nate of murdering Beck. Nate says that he knows who the killer is, and says that everyone had a motive. Hammett figures that Nate had a motive as well since he was arrested for threatening an IYS CEO. In response, Nate explains that the killer knew about the secret passages. Since the killer knew Beck would be drunk, they got into position and planned to make Beck's death look like a murder. When Beck died, the power went out before the lightning struck. Nate figures that there are two killers, and that they cut the power at the main junction box in the pantry. Hayley wanted to get her hands on the family fortune before Beck lost it due to the lawsuits, so she convinced a lug to help her and then she pulled the switch while her partner killed Beck. The only thing that ruined it was Nate being there. Nate asks to see Hammett's badge. When Hammett shows him his badge, inside his jacket, Nate says that he saw it on the killer, meaning that Hammett is Hayley's partner.
Hammett prepares to shoot Nate, and Nate admits that it's a safe play. However, he warns that there's one problem. The lights go out again and Nate ducks into the secret passages. He finds Hardison and Parker and they head out. Hammett follows them and opens fire. Hayley comes to investigate and Sophie knocks her out. Case finds her and figures something is up.
Nate goes to the library where Sophie was handcuffed. Hammett comes in after him and Nate knocks him out from behind with the pipe wrench that Potter hid earlier. He then calls Detective Bonnano.
Later, Sophie, Nate, and Judy gather at the bar and watches Case on the news as he gives a press statement about Hayley's involvement in her father's death. Judy is happy that Case agreed to settle for $60 million given that he won $100,000 for winning the murder-mystery competition. Once she leaves, Nate pours himself a drink and Sophie admits that she's relieved he's not the killer. He points out that each of his teammates thought he might do it, but Sophie assures him that none of them really think that. Nate pours himself another drink and Sophie leaves. As she goes, she tells him that he might be drinking again because of what he thinks of himself, not because of what they think of him.