Santa Claus tasks Billy Eichner, his trusted elf-secretary, with lifting everyone's spirits and reviving Christmas joy for the season. He rings up a famous friend, Mariah Carey, who is busy setting up Christmas in her New York City apartment with her two kids, Roc and Roe, and her daughter Little Mimi (Mykal-Michelle Harris). Little Mimi is not as enthusiastic about Christmas as the others, which gives the story its gentle tension.
Carey receives Billy's urgent plea and quickly reveals a sleigh hidden behind her fireplace, a magical invitation that sends her rushing off to help Billy. Arriving at the North Pole, Billy explains that holiday cheer is at its lowest point ever. Carey suggests that staging a festive Christmas concert could lift spirits worldwide, arguing that she has the experience and stage presence to pull it off. They begin assembling a setlist, with the moment framed by the idea that When Christmas Comes is the emotional core of their plan. Just then, Woodstock-like interruptions appear as the antennas on the TV are adjusted to reveal a Peanuts segment where Linus and Charlie Brown realize that what they miss most is time spent with friends and family, a reminder echoing the season's message that Christmas time is here.
Back at Carey’s cabin, she slips away from the toy factory to observe the elves at work, triggering a moment of panic for Billy as the clock ticks down. She is soon joined by a star-studded group—Ariana Grande (Ariana Grande), Jennifer Hudson (Jennifer Hudson), Snoop Dogg (Snoop Dogg) and Jermaine Dupri (Jermaine Dupri)—as they accompany a sequence of festive numbers including Oh Santa! and Here Comes Santa Claus (Right Down Santa Claus Lane) and House Top Celebration. The energy peaks with a Sugar Plum Fairy ballet performed by Misty Copeland.
As the stars shine, Carey and Billy wander into the forest and take a wrong turn, losing their way until they follow a guiding star and eventually find their path back. The pair’s journey culminates with a return to Carey’s New York apartment, where she wakes to tell her children it was all a dream, only to discover that Billy has appeared and is ready to kick off the Christmas concert. Mid-show, an unexpected power outage plunges the stage into candlelight. Carey adapts, delivering a heartfelt moment with a quiet rendition of a classic carol, and a message about celebrating love and light after a difficult year. The show closes on a high note with an encore and Little Mimi reclaiming her love for the holiday, as the beloved tune All I Want For Christmas Is You fills the room and the city outside lights up with festive spirit.
