After a Department of Justice investigation into the plane explosion, Peter gets his badge back but with strings attached. Diana reports that Fowler was handed over to OPR two days ago, then disappeared. The data from his laptop self-destructed when she hacked into it, but she was able to retrieve one entry: a date, a time and a place. Fowler is expecting something to happen two months from now.
Neal has been back in prison since the explosion. Peter can reinstate their consultant deal if Neal accepts the tracking anklet again. Peter also insists that Neal leaves finding Kate's killer to him.
Two months later, Neal "robs" a bank in a test of its security system. He poses as a new employee and lifts the receptionist's electronic access card. Then he enters the vault and fills a briefcase with stacks of cash, discarding stacks containing dye packs. Outside the bank he gives the money to a waiting Peter and Jones.
At the office, Peter, Neal, and Renee Simmons meet with five branch managers from Midtown Mutual Bank. Renee, who is in charge of security for the bank, requested the test. Neal points out several flaws. Among them are the receptionist's clipping her access card to her waist where it could be easily lifted, and the easily recognizable dye packs. In the past week each of the five managers had received a business card signed "The Architect". The FBI believes it's the same person who's robbed banks in Dallas, Boston and Chicago. If he sticks to his MO, the vault at one of these Midtown Mutual branches will be emptied within a week.
Peter sees visible signs that Neal is still deeply shaken by Kate's death. With everything riding on Neal's job performance, Peter expresses his concern to Mozzie. Asked if Neal thinks Kate's killer was after him, Mozzie says the thought has crossed Neal's mind.
As he and Neal review the search for Kate, Fowler and Operation Mentor, Mozzie says he hasn't heard from Alex Hunter since the explosion. The FBI evidence log shows that Diana logged in the music box in New York after Peter recovered it from Fowler. Neal wonders if the box is still in the evidence locker. Kate's killer isn't going to let it just sit there.
The Architect's card contains a Cyrillic-looking but unfamiliar "A". Neal determines that the robber is a fan of a Russian painter named Ivan Aivazosky, and copied the A from Aivazosky's signature. Diana checks past art auctions for Aivazosky bidders who also have a business connection in Dallas, Chicago and Boston. One person fits the bill: Edward Walker.
At Walker's penthouse, his assistant Whitney escorts Peter and Neal onto the patio where Walker is hitting golf balls. When Peter asks Walker for an alibi, Walker asks Whitney for his calendar which she keeps on her cell phone. With irritatingly smooth arrogance, he then offers to answer the question if Peter gets a warrant. As Peter and Neal leave, Walker adds, "Oh, and Mr. Caffrey. A suggestion for the next time you commit a crime. Don't get caught."
Neal is certain that the wealthy Walker is the Architect. He's committing these robberies for the fun and the satisfaction of putting one over on the police. Concerned that Walker got under Neal's skin, Peter warns Neal not to do anything stupid.
Later Neal "runs into" Walker's assistant Whitney, and with Mozzie's help surreptitiously copies Walker's calendar off her cell phone. Walker has an appointment at First Unity Bank at noon the next day.
After Neal tests the security, the FBI stakes out the bank. Renee Simmons is with them. At noon an alarm goes off, but it's only an alarm clock inside a safe deposit box in Peter's name. As a crestfallen Peter and Neal stand on the sidewalk, Walker comes along with three associates and cheerfully says hello.
Having trusted Neal's illegally obtained lead, Peter is really on the hot seat now. The two of them start at the beginning, trying to figure out the Architect's game. Why would he send a business card to warn the bank? Neal says it was a test, to see what they'd do. Peter realizes they reacted by testing the bank's security, thus revealing its weaknesses.
Peter's phone rings with a call from Jones, who tells him to turn on the TV news. Alarms have gone off in 36 banks throughout the city. Since none of them received the Architect's card, they're just a diversion to tie up the police response. He's still targeting one of the five Midtown Mutual branches, where everything is silent. Peter then remembers that Renee had followed Neal's advice to change the vault access codes daily, instead of weekly. The Architect can't get into the vault without her.
Peter and Neal race to the branch where Renee works. Through the locked front doors they see two masked men dragging off an unconscious bank guard, and two more men holding Renee at gunpoint. They slip inside and are able to rescue her, but the four robbers empty the vault and make a clean getaway.
Back at the office, Peter and Neal study the bank security video as Jones reports that $8.2 million was taken. Neal looks at the video again and realizes that something literally doesn't add up. The four robbers each had two briefcases, and the stolen money was all $100 bills. The eight briefcases held a total of only about $6.5 million. More than $1.5 million is unaccounted for -- enough for a share, perhaps?
Renee meets Peter and Neal at the bank and takes them into the vault. Two months ago a safe deposit box was rented to Renee's uncle -- who died two years ago. Renee must have forged the application. The bank president gave Peter the bank's key to the box, and Renee hands over her customer key. As Peter opens the box with Neal watching, Renee pulls a gun from her purse.
The box is full of cash, which Renee orders Neal to put in a bag. She was in on the robbery, and had put on an act for the security cameras. Walker had convinced her that a big payday now was better than a mediocre pension later. As Neal fills the bag, he and Peter notice that two of the money stacks are dye packs. Notwithstanding that they're being held at gunpoint, they begin arguing loudly to distract Renee. When she totally loses her cool and yells "Shut up!", Neal claps the dye packs together and showers Renee with dye. She's momentarily blinded, and Peter disarms her. After Renee implicates Walker, he is arrested too.
Later, Peter meets with Mozzie again and says that he can clean up a mess after it happens, but not stop one before it starts. For Neal's own protection, Peter wants Mozzie to tell him whenever Neal's about to do something stupid.
Mozzie tells Neal that something's happened with the music box. It spent two hours in the New York FBI office before OPR requested it be transferred to Washington, DC. Somewhere in transit, it vanished.
It's almost time for Fowler's meeting. Peter phones Diana as he leaves the office. She says, "Right behind you, boss" and takes her gun out of a wall safe, which also contains the music box.