The episode begins at Naval Air Station -- Base Housing. We see that a woman, a Commander, comes home for the holidays and finds her neighbor stringing lights. She enters a dark house with a pile of mail and a terrible smell and also a dead husband in an easy chair! Next morning the team arrives at the scene and Megan Huffner, the Commander, explains to Gibbs that she last spoke to her husband Pat, at Thanksgiving and she'd been deployed in the Gulf for six months. She tells them that Noel was an unemployed Navy husband. There's no sign of forced entry and he's been there three or four weeks and there are no visible wounds.
Back at the office, Tony gets a notification that his dad's flight into town has been delayed. He is not looking forward to the visit, which he knows is bound to lead to an argument. Noel’s employment record is spotty and he was always the strange one in the family. There is no criminal record, except for a minor one in ’09. Abby is decorating the lab and she is setting up an entire village! Palmer brings her the victim's personal items including a phone and cash, including a weird looking $100 bill. At the Bureau of Engraving and Printing, Gibbs and Tony learn from Assistant Director of Operations Donald Linder, that the bill is authentic. He wonders how NCIS got it as it wasn’t put in circulation yet or even left a Treasury building.
It has all the latest security features, including color-shifting ink, raised printing and a 3-D liberty bell which is counterfeit proof. It was supposed to be introduced in February 2011, but there were production problems, including creases in the notes. It is possible fully 30% of $110 billion in bills were printed with flaws. Tony's dad calls. He tells him to take a cab. The bill's serial number is from a batch that was shredded 18 months ago. Secret Service Special Agent Ashley Winter arrives, she says she's taking the $100 as evidence, but Gibbs doesn’t let her do so. Back at the office, they can't connect Noel to the Bureau of Engraving and Printing. Abby brings in Anthony DiNozzo Sr. He informs Tony he is staying with him. In the morgue, Duckie tells Gibbs the cause of death was a broken neck.
Noel was also a heavy drinker. At Tony's place, he has a flat screen and grand piano but no decorations. He calls his goldfish Kate. He has a large modern kitchen, with only pizza and water in the fridge. He has lived there 12 years. Tony sets his dad up in his bedroom, with a twin bed without enough room “for play”. In the lab, Abby found Noel's print on the $100, and the second one belongs to Justin Cannady, who was fired from the BEP. Ziva and McGee report that the Secret Service had Justin’s place locked down. Tony says that Justin had horrible credit and was broke. Agent Winter arrives to brief them on Justin, who was fired for being drunk on the job. He lost two fingers on the job while operating a shredding machine and so Linder had to let him go.
She reports they found nothing at Justin’s. Gibbs won't let her people go through Noel’s house. Megan tells Gibbs and Ziva that her husband over-drew their credit cards. He was always at Gillespie's Saloon. At the Huffner's, Tony gets McGee to crack his back which is in a bad shape due to falling off from the couch. Tony Sr. calls Tony to ask where his roasting pan is. He's preparing a traditional DiNozzo Christmas dinner. Tony tells McGee about his dad never used to be around a lot and his dad broke the tradition of passing down a signet ring on the son's 21st birthday; which he never got. He thinks his dad pawned it during the bad times. McGee inspects a dying plant and finds a false bottom with a bag of the new $100 bills.
Gibbs and Ziva head to Gillespie's, where the owner says Megan calls the bar when Noel never answered her calls. Gibbs likes the owner’s old time pick-up truck. He says Noel and Justin were like Cliff and Norm and that he hasn’t seen both of them in a while. Tony comes home to find his dad trimming a Christmas tree. He moved Tony's piano and baked snickerdoodles using Tony's mom's recipe. Tony is not too happy as his space is now being intruded. His neighbor lady knocks at the door and Tony tries to ignore her. Tony gets a text that Justin’s body was found. They find his body crawling with maggots. Gibbs gets annoyed when Agent Winter shows up. He diverts her from the body.
Back at the office, they find that Noel had $400,000 in the new $100s. They wonder if Noel bought the $100s at a discount because Justin could not use them until they were in circulation. But then why are they both dead? In the lab, Abby tells Gibbs that there are fibers on the bills that indicate that the new bills left in the trash. Agent Winter comes down to the morgue to ask if the body has been IDed as Justin’s. Duckie distracts her while Palmer calls Gibbs down. Duckie reports it is Justin and his neck was also broken about three or four weeks ago. Gibbs and Winter go back to talk to Linder, who doesn't understand how the money got stolen. He says the money was destined for the Adam County Landfill in Virginia. Back at the office, Tony Sr. comes by in a Santa hat, bearing gifts.
He tells Ziva he might be trying to make up for too many missed Christmases. At the landfill, McGee is surprised to recognize Stewie, an old MIT classmate who says he found his calling in trash. He tells Tony that McGee was the school mascot, a beaver. Stewie recalls where the trash from the date 18 months ago is buried, and he remembers they had a break in that night, followed by an investigation. He remembers the date because it is the night the SEALs killed Bin Laden! Tony comes home to find even more decorations. He is impressed and thanks his dad. But then he opens the door to his bedroom and sees his dad busy with his neighbor. "I'll have to burn the bed now," Tony says. He says that it was almost like old times; but this got a little too far. He says that it was a mistake having his father home for Christmas as he broke the rules of his house.
He wants his dad to leave. The next day, McGee tells Gibbs that the night of the break in was the same when Bin Laden was killed. This means that there would have been increased surveillance in the DC area. Gibbs calls Winter, who is in Linder’s office, to access archival surveillance of the DC area, which was stepped up that night after the raid. At home, Tony says good-bye to his dad. In the lab, they watch the surveillance footage of the landfill break-in. It is dark and poor quality, but Gibbs recognizes the old pick-up that belonged to the owner of the Gillespie’s. Back at Gillespie's, they serve the owner with a warrant to search for $100s. Gibbs thinks Gillespie stole the money with Justin, and then killed him when he sold some of it to Noel.
Gillespie is a retired Marine and could have accessed Noel’s house on the base. Gillespie watches nervously as Ziva searches his office. He tells them where to find his safe. Stealing the money was his idea. He is arrested. Case Closed. Next, Tony tells McGee he's not in the mood for "It's a Wonderful Life" and he left the DVD at home. He goes home to get it and sees his dad's Santa hat and a photo of his mom. He turns on his tree and sees a small box under it; it is the signet ring. Later, in MTAC, they watch as Agent Winter takes full credit for the investigation at a news conference. Tony joins them late. He thinks his dad wanted to make amends and he blew it. Abby arrives with Tony Sr. in tow. Tony hugs his dad and tells him he loves him. The episode ends.