The Duck Family prepare themselves for Christmas, which in this case means setting traps for Santa Claus, with whom Scrooge has a heated rivalry. Della informs Huey, Dewey, and Louie about it, but it quickly becomes apparent that she has no idea why he hates him. Webby is also determined to deter Santa from coming to their house; denying anything jolly about Santa's appearance. To everyone's surprise, Santa, who is as jovial as depicted, comes through the front door and appears to be severely injured with a wounded leg. He informs Scrooge that he needs help delivering the gifts for Christmas, and Scrooge reveals why he and Santa are enemies: Santa "stole" the idea of Christmas from him. He reluctantly concedes, having apparently helped him before, but insists that only Webby come along as she is the only child who is not charmed by Santa's whims.
In flashback throughout the episode, Scrooge is trying to make money selling coal to houses, but fails due to his brunt attitude. He meets Santa Claus, who is trying to give away gifts to people, and manages to charm his way into a house belonging to elves. Santa and Scrooge quickly become friends with the latter suggesting they go into business as "McDuck and Claus Deliveries". They decide to start selling gifts by Christmas Day by retrieving the Feliz Navidiamond, an ancient relic that can slow down time. They tame wild flying reindeer and battle a monster snowman and succeed in their quest. When Santa suggests giving gifts away for free, Scrooge is angered by this and selfishly refuses. Santa tries to convince him that they can warm their hearts, but Scrooge says that they're supposed to warm their houses and asks who cares about their hearts, which Santa takes an offense and says he cares and tells Scrooge that he continues his work and reluctantly leaves Scrooge behind. Infuriated, Scrooge leaves Santa too and leaves, with the elves staying with Santa to help make toys for him.
Back in the present, Santa, Scrooge and Webby make their way dropping presents off at houses. Over time Santa and Scrooge reminisce on old times and start becoming friendly again and Webby starts to become charmed by Santa when he reveals that he got her a new crossbow. They stop at the final house where Scrooge decides to enter alone to give the last gift. As Webby searches Santa's bag, she finds that none of the presents have been dropped off and that Scrooge had switched them all out with coal; still convinced that it is a more practical gift than actual presents and apparently unaware that it is considered a gift for bad children.
Scrooge presents the coal to a little girl named Jennifer, who instead fashions it into a doll, annoying Scrooge. He tries to explain how practical coal is, but upon seeing the happiness in Jennifer's eyes for having a rather simple trinket, Scrooge sees the error of his ways and finally understands what Santa has been trying to tell him all these years. Santa and Webby angrily confront Scrooge, as they admonish Scrooge for ruining Christmas, with the former revealing that not only did he fake his injury, but he brought Scrooge along as he hoped that it would bring him out of his miserable shell and make them friends again.
Feeling remorseful for being such a selfish miser, Scrooge apologizes for his selfish behavior and they recruit the rest of the Duck family to re-deliver the gifts on time. Santa gives Scrooge jingle bells with the "McDuck and Claus Deliveries" logo on it that reminded them of their time together while Scrooge gives Santa car keys that are actually to turn off the traps in his mansion. Scrooge welcomes Santa to come to his home anytime he wants as long as he goes through the front door, thus ending the rivalry between Scrooge McDuck and Santa Claus, with Scrooge asking him not to come like creep, Santa hugs, while Scrooge joyfully says:"Ho Ho Ho!"
- David Tennant as Scrooge McDuck
- Danny Pudi as Huey Duck
- Ben Schwartz as Dewey Duck
- Bobby Moynihan as Louie Duck
- Kate Micucci as Webby Vanderquack
- Beck Bennett as Launchpad McQuack
- Paget Brewster as Della Duck
- Tony Anselmo as Donald Duck
- Toks Olagundoye as Mrs. Beakley
- Lin-Manuel Miranda as Fenton Crackshell-Cabrera
- Hugh Bonneville as Santa Claus
- Abby Ryder Fortson as Jennifer
- Kimiko Glenn as Lena
- Libe Barer as Violet
- Eric Bauza as Bouncer, Big Time, Beagles
- The title is an obvious and similar nod to the Dr. Seuss' story How the Grinch Stole Christmas. At one point near the end of the episode, Santa refers to Scrooge as a "Grinch".
- This is the final episode to air in 2020.
- The Legends of Legendquest II is a possible reference to both The Legend of Zelda and Dragon Quest.
- Bouncer of the Beagle Boys is revealed to be the "good one" of the entire group.
- Violet and Lena share a bed together.
- Della is revealed to sleep in Donald's houseboat.
- "Feliz Navidiamond" is, of course, a play on "Feliz Navidad" (Spanish for Happy Christmas).
- Eleanor Roostervelt is a play on Eleanor Roosevelt.
- Jennifer is a reference to the Uncle Scrooge comic story "Tis The Season" by Bob Foster & Mike Peraza where Scrooge reads letters from her that he had collected over the years.
- Scrooge instead of Santa says "Happy Christmas to all, and to all a good night!", the last quotation the latter said in The Night Before Christmas.
- The reindeer vaguely resemble Sven from the Frozen series.
- The Christmas version of the opening theme (previously seen in the episode "Last Christmas!") is used again for this episode. The only difference is with the Season 3 addition of Della in the opening credits.