As the episode opens, we are shown facts about the Holocaust relating to artwork. As this fades, we cut to the museum where a man is steadily walking through the museum, going past the motion detectors and lasers, as well as the security guard. When he moves, the guy changes the camera to a taped session of the area. But the security guard notices the times are different on the camera and on his clock, then calls to the security guard to check that area, but he won't respond. Meanwhile, the thief disarms some layers around a painting and steals it before the security guard appears. He is hit with a taser, and as the thief heads for the elevator, we see the previous security guard patrolling the area was also hit by a taser gun, as well.
As Don and his team appear, David tells Don that the thief got away with a Pissarro painting, worth $22 million. As Don says the name of the painting, "Paris au Printemps, Apres-Midi," David is surprised that he can speak French. They both meet up with the curator, Arthur Ruiz. He tells David and Don that the Pissarro was the most valuable painting the museum has acquired, it was scheduled to go on tour the next month, and the donor of the painting, who would collect the insurance, is out of town.
Meanwhile, Charlie and Alan are clearly not getting along when it comes to cleaning. Alan gives Charlie a list of the things that need to be done in the house, and Charlie leaves.
At the FBI headquarters, David tells Megan that nobody's name is really popping out on the list of employees. That's when Jack Tollner from the FBI Art Theft unit arrives with Don. He explains how the art piece would be difficult to move, because of its provenance, or "paper trail of ownership." The painting has a tainted provenance, since it's not the first time the painting has been stolen. The first time was by the Nazis.
When the Nazis took over Germany, they made the Jewish population register every piece of property, and they stole them later on, after families were deported. Megan decides to look at the art theft database about the Pissarro.
Meanwhile, Charlie and Larry prepare for a "show-and-tell" day, with some help from Amita, as Don realizes. He informs them of the stolen painting. So, Charlie decides to use a Quadratic Discriminant Analysis to compare the theft of the Pissarro to other robberies.
Megan gets an idea from the art theft database. A lady named Erika Hellman found out the owner, Peyton Shoemaker, was selling the Pissarro and sued him, claiming the Pissarro was hers and she lost it to the Nazis. She lost the case, however, due to credibility. She's 78, but she could've hired someone to steal the painting.
Megan finds out Ruiz knew about the Pissarro's past. Meanwhile, Don talks to Mrs. Hellman about the painting and how her father said that they were like the family in the painting and promised they would go to Paris sometime, but it never happened. She says she didn't steal the painting, but she would've loved to have it back. Her family was taken from her and she doesn't have one picture of her family. However, when she looks at the Pissarro, that looks like a family portrait to her. Don sympathizes for her. That's when her grandson, Joel Hellman, comes out. He's very angry about the fact his grandmother's claim was denied. However, she says that she didn't lose the case because of the law, but because her memory is fading. She had a huge family, but she was the only living member who actually saw the painting. The court wouldn't believe that. She says that the Pissarro has run through her mind many times, but she never thought of stealing it. Her mind is thinking about why she lost her family now.
Larry, Amita, and Charlie are investigating the theft, when Larry gives some amazing facts about Pissarro's life. He reveals that his own father was a painter and wanted him to be one, too, but he wasn't interested in "seeing the world the way he does." Charlie mentions his quarrel with his dad about the cleanliness of his house. Amita finds three similar robberies that have three different suspects. When Charlie presents this to the team, one of the suspects is in prison and another is dead. That narrows it down to Ronald Wheeler, a Canadian citizen, but he has no record of entering the country. They decide to give out his picture to all the hotels. They get a hit and come to his room. When he doesn't answer, David and Tollner enter, only to find Wheeler dead.
Don, Jack, and Megan are talking about Mrs. Hellman's claim, then decide to pay the owner of the painting, Peyton Shoemaker, a visit.
Alan is surprised to find Charlie home. He asks about the list. Charlie says he's been busy. Alan tells him that he had many more responsibilities when he was Charlie's age. Charlie leaves by saying he doesn't need a lecture on how to run his life. When he leaves, Alan finds the pictures of Nazis and the camps, and gets a very peculiar look on his face.
Peyton Shoemaker tells Don and Megan his father made the purchase in Paris when he was on leave from the army after WWII. He got it for $12,000. He really doesn't know where it comes from and it's difficult to figure it out. He gave a settlement to Mrs. Hellman, but her grandson threw the offer in Peyton's face.
Don goes to Charlie at Cal Sci and finds him balancing the checkbook. Charlie doesn't want a lecture from him, but Don doesn't say anything. Don talks to Charlie about the fact that they were never religious, and they don't know why. Don asks Charlie to figure out where the Pissarro is heading. Charlie tells Don that there are still a limited amount of options. He'll use a Diffusion Map to figure out where it can go to limit the options.
David tells Jack and Megan that they might want to look at the grandson, Joel Hellman. He hired a private investigator, Peter Teusche, who has pending charges in Istanbul, similar to the crime that Michael Ness, one of the robbers Charlie pulled up, is doing time for. He shows Megan and Jack an MPEG file of a picture of Joel looking at the Pissarro with a very peculiar look.
Joel tells Don that when he hired Teusche over three years ago, he lost his temper. It was a stupid thing to do. He was upset about how the court had doctors come in and test his grandmother's memory, making her live through the horrors of her life again. As for his presence at the museum, Joel says that when he saw it, it just made him feel better about his grandmother, knowing that the painting is not destroyed, but still is kept somewhere to be adored.
Don really doesn't believe that Joel did it. So they're back to Shoemaker and the possible insurance scam.
Amita tells Charlie and Larry that the Nazis stole over one-fifth of European artwork at that time. Charlie's suddenly finding a heavy flow of work leading to China. Just then, Charlie's cell phone rings and he turns off his cell phone. He tells Larry, "it's a standoff." Larry says that most fathers think their sons will be a legend in their shoes, when they can do so much more.
Don comes home for dinner and finds Charlie isn't there. Alan talks about how Charlie just can't keep up with house cleaning. Don talks to him about Erika Hellman, and how it seems nobody ever thought she had a life. She finds something that was once a part of it, and it's taken away from her again. Alan says his mother's cousin, Anna, experienced the same thing. She managed to survive, but she looked for her family her entire life.
Charlie meets with Larry for breakfast and finds him looking at paintings he did. Most of them are copycats of other masterpieces. Charlie says the lead to China came up empty. Larry explains to Charlie that maybe the Pissarro was not for sale because of some problem it had. Charlie wonders what that could be. Then, he gets an idea and leaves.
Charlie meets with Megan, Jack, and Don. He says he used a computer program that analyzes paintings, first using "Craquelure," or the cracks that make up the surface of the painting, giving them an idea when the painting was done. Also, they use Visual Style to find out the signature of an artist's painting. That gets help from Curvelet Analysis, allowing them to look at the actual brush strokes of the painter and the contours of each of these strokes, giving them an idea of the painting style in 3 Dimensions. He compared his results with other Pissarro's paintings from museums around the world, bringing him to his conclusion: the Pissarro stolen from the museum is a fake, not painted by Pissarro.
David and Megan talk to the curator, Arthur Ruiz, who refuses to believe the Pissarro they acquired is a forgery. It was authenticated and cleaned since it arrived under strict supervision, which highly doubts someone switches it out. Megan and David talk to the museum conservator, Patrick Holden, who authenticated the painting when it first arrived and cleaned it 18 months back. He's sure that the Pissarro he authenticated was the same as the one he cleaned. Holden also did the museum catalogue, and the picture of the Pissarro was given by Peyton Shoemaker.
Don, Jack, David, and Megan talk about the possibility Shoemaker made a forgery to protect his painting from theft, or losing it to, maybe, the Hellmans. Alan meets Charlie at work and decides to make peace with him. He tells Charlie he just wants him to have a steady life and nothing go wrong that he ends up like Larry, living in his car. Charlie's afraid that might happen, too.
Megan is at Peyton's house with a warrant. Peyton thinks the math expert who analyzed his photograph was hired by the Hellmans, but Megan tells him the math expert works for them. They don't find anything at his house. Peyton tells Megan he won't break his father's honor by becoming a criminal. He didn't do anything.
Don, Jack, and Megan decide to look for a forger. Jack tells Megan that many people are capable of doing this. Megan says they can run the painting against the art theft database. Jack says that still a lot of names to run down. Megan says that instead of the names, they can give Charlie the photographs of paintings that have been seized over the years and see who matches up. Jack responds, "If [Charlie] can tell us Pissarro didn't paint the fake, he can tell us who did." Charlie does the analysis and comes up with a match to Gustav Stahlberg. The problem is, he's been in a Jewish cemetery at Budapest since 1948.
David gives the file of Stahlberg to Don, saying that Stahlberg was convicted of fraud in 1946, died in prison two years later. Hungarian police seized five, assumingly, forged paintings, one of them being "Paris au Printemps," the Pissarro. All 5 paintings were assumed fake, but the real Pissarro was there, and got locked in a Hungarian police vault for almost 60 years. Jack gets the idea Mrs. Hellman's father paid Stahlberg to paint the fake, then gave him the real one for safekeeping. Megan says Shoemaker probably said the truth: he didn't know the Pissarro was a fake, no one did. Don still refuses to believe that a painting, which was a forgery, was stolen a month before it was scheduled to go on tour.
That sends Megan back to Patrick Holden, the museum conservator. She and David talk to him for a second time. He says he must've made a mistake, thinking the Pissarro was real. Megan refuses to believe that. He's been doing this job for 20 years. How can he make a mistake? Patrick knew that Pissarro was a fake and withheld that from them. He says he didn't steal it for money, but to save his reputation, because it would ruin him and the museum. Who told him this? Arthur Ruiz, the museum curator.
Megan, Jack, and David meet him at a party after arresting Holden. When Patrick told him the Pissarro was a fake, it was too late. The Pissarro had given them some fierce publicity. Ronald Wheeler found the Pissarro was a fake, and blackmailed Ruiz, which is why he got killed. Ruiz thought if the painting just disappeared, it would be better. Shoemaker's insurance would pull through and the museum could look forward to a future. Not anymore. Megan arrests Ruiz.
Don gives the painting, just delivered by Hungarian police, back to Erika Hellman. She's absolutely overjoyed, along with her grandson. Don says her father was one of the few who knew what was going to happen with the Nazis, which is why he had Stahlberg paint the fake. Absolutely amazed she finally got the painting after all these years, she wonders if what she saw was true. Don gives her his sympathy, hoping she would find some closure. She definitely will.
Larry talks about the kids in the Holocaust. The world around them seemed safe, and then, all of a sudden, everything that they had disappears. For Mrs. Hellman, the painting was enough to somehow bring her family back to her. Don arrives, and Alan tells him they're going to be having something barbecued. He asks Charlie if he got some more propane since they're out. Charlie thought Alan would take care of it. Just kidding! He bought a new tank. He leaves to take care of it, and Larry goes to help him out. Don tells Alan he might be able to find someone from his mom's cousin's family. He just needs a list, which Alan can definitely provide. Alan finally has some hope in his face.