Set thirteen years after the first film, this black comedy revolves around Willie Soke, who is as bitter, depressed and drunk as ever.
Resentful that his 'happy ending' did not work out, he finds himself addicted to sex and alcohol once more. As he tries, and fails, to kill himself, he is visited by Thurman "The Kid" Merman, who has just turned 21 and works at a sandwich shop. Unfortunately, Thurman's father has abandoned him and his grandmother is no longer living - making Willie the closest thing to family he has left.
Thurman delivers to Willie a package containing a large sum of cash, and Willie soon finds out it's from Marcus, his former partner who has been released from jail after the events 13 years earlier. Marcus, expressing sincere remorse for betraying Willie, tells Willie he has an opportunity in Chicago, a deal that can potentially net them millions, though he is unwilling to disclose the name of his contact. Willie reluctantly agrees, while unsuccessfully trying to help Thurman lose his virginity before he leaves for Chicago.
Upon their arrival, Willie is annoyed to learn that not only is a target of the con a charity, but that his estranged mother, Sunny, is Marcus's contact. Willie reluctantly agrees, since Sunny is suffering from early stages of Parkinson's Disease, though he secretly makes a deal with Marcus to cut Sunny out when the time comes.
Forced to don the Santa suit once more, Willie is arrested when he beats up another Santa (after a misunderstanding causes Willie to think the other Santa is a pedophile) but is bailed out by one of the charity's founders, Diane. Though she wants to fire Willie for his behavior, she relents when he agrees to attend AA meetings with her. Diane's husband Regent, who also runs the charity and is cheating on Diane with his secretary, orders his head security guard Dorfman to track and follow Willie, becoming suspicious of how much time he's spending with Diane.
Meanwhile, Marcus, after doing recon work, tries to seduce Gina, another security guard so he can obtain the keys to Regent's office where the charity's safe is kept but he fails to do so as Gina is high maintenance. Elsewhere, while Willie starts a sexual relationship with Diane, he and Sunny start to bond, especially when they pull a job just between the two of them, robbing a mansion with Willie posing as Santa and Sunny as Mrs. Claus. Bonding over their haul afterward, Sunny gives Willie a gun so he can betray and take revenge on Marcus despite Willie’s insistence that Marcus has changed.
Thurman soon arrives in Chicago, having followed Willie to the city. Willie at first considers leaving him at a laundromat but soon takes him to the shelter at the charity. Thurman ends up joining the children's choir, which is set to have a concert on the night of Willie, Sunny and Marcus's heist. Willie soon encounters Gina, who, thanks to Sunny's prodding, believes Willie wants to sleep with her. They have sex in the bathroom of a bar, and Willie obtains the keys.
On the night of the show/robbery, Willie catches Thurman singing, which makes the kid very happy. As Willie cracks the safe, Marcus is about to betray him again, but they escape just as Regent and Dorfman discover the con. However, Sunny reveals she is betraying them both, telling Willie the bullets in the gun she gave him are blanks before shooting Marcus.
She tries to escape by disappearing into a crowd of people dressed as Santa at an outdoor party. Willie, Regent and Dorfman chase her; despite her blending in, Willie catches her and attempts to take the bag of stolen cash by saying the kids need it more. In their struggle, the bag is torn open and the money goes flying into the crowd. Enraged, Sunny attempts to shoot him again, but hits Thurman in his behind instead.
Both Sunny and Willie are arrested, but Willie is not charged due to his help in catching Sunny. While he recovers, he is visited in the hospital by Diane who wakes him up with manual pleasure.
Willie soon takes a job as a janitor at the charity, where he continues to visit Thurman and accepts him as family. He also visits an injured Marcus, proceeding to 'tea bag' him and post pictures of him doing so on Instagram, as revenge against Marcus for doing the same thing to him.