Widower lieutenant Harry Patterson has just been selected for a top-secret mission. Since the death of his wife, he has been home taking care of his 9 year old autistic son Ben. His daughter Kami (19) is a premed student at Yale University. Because of Harry’s deployment, Kami is forced to finish her fall semester early and come home to take care of Ben (“Just Fly”). Harry helps Ben compose a letter to Santa (“Dear Santa”) to mail that evening at the Village Tree Lighting Festival. At the tree lighting, Harry neglects a call from base which causes Ben to have a meltdown and miss the main event (“Cue Christmas”). When Kami arrives home, Ben realizes Harry is leaving and begins to shut down. Harry comforts him with a familiar song from Ben’s mother (“Night Like No Other Night”) and reassures him with a special compass ensuring they are always connected. After Harry leaves, Kami urges Ben to make the best of the situation (“Practice Makes Perfect”). Upon arriving in Greenland, Harry’s unit is given instructions to clean up subarctic nuclear waste and learns he is not allowed to communicate with home. Uncertain of Harry’s whereabouts, Ben tears down the Christmas decorations, anxiously reciting all of Harry’s previous deployments and frustrated that he doesn’t know the current one (“Tell Me”). In his special hideout atop a bookcase, Ben finds comfort imagining his mother’s presence (“Born to Believe”). Meanwhile, out on the Greenland ice cap, Harry unknowingly stumbles upon the North Pole. He is quickly sent away by incognito elves Snicker and Charley who are determined to keep his visit a secret (“In the Dark”). Arriving back at base, Harry is informed that his radiation levels are too high and is placed in an isolated hut outside the camp. As the days pass, Ben regresses and becomes nonverbal. Kami worries of her ability to meet Ben’s growing emotional and mental needs (“Say Something”). Ben is convinced that Harry must be home for Christmas. He remembers writing the Santa letter and decides to send an updated version requesting that Harry meet him at High Falls on Christmas Eve. After sneaking off to the Village Square to mail the letter, bullies break his spyglass (a tool to him stay focused) and leave him lost and afraid. In his barracks, Harry dreams of Ben being lost (“Come Find Me”). Kami finds Ben in the Square and warns him never to leave the house alone again. In his barrack, Harry awakens to find a note: “Come find me.” Determined to find the sender, Harry sets out across the ice cap but quickly succumbs to the elements and collapses. He awakens in North Pole Central Intelligence and is made privy to his location by Snicker and Charley (“The Best Kept Secret That Everybody Knows”). As Christmas Eve arrives, Ben sets out for High Falls, confident that the request of his letter will come to pass. (“Night Like No Other Night Reprise/Make It Happen”).
While double checking Santa letters (“Kids These Days”), Snicker discovers Ben’s letter and the dangerous plan he is undertaking and rushes to tell Harry, who has almost given up on ever returning home (“Never Ending Road”) Snicker offers to sneak Harry home in the sleigh, but a final reindeer grooming renders the sleigh grounded. However, when Harry gets close to the sleigh, the magic meter flickers. They discover Harry’s radiation is a valid source of energy to run the sleigh and take off for the Southern Yonder (“The Day That I Hijacked Santa’s Sleigh”). Meanwhile, Kami discovers Ben is missing and searches for clues to his whereabouts (“If I Were Ben”). On top of the bookcase, she finds scraps of Santa letters indicating he’s headed for the treacherous High Falls where her mother died. Overcoming her own fears, she rushes to find him. Following his compass in the forest, Ben enjoys his independence and revels in nature (“Sensational”). As the trail gets increasingly difficult, he trips and loses his compass. Overwhelmed, he finds a place to hide. After a reluctant journey up the mountain, Kami finds Ben and they finish the hike to High Falls together, unaware that Snicker and Harry have just arrived in Cherry Springs forest. Powering the sleigh has depleted his radiation, so Harry safely heads towards High Falls to find Ben. Without a source of energy, Snicker is uncertain of how to get the sleigh back before evening (“The Day That I Hijacked Santa’s Sleigh Reprise”). When Harry reaches High Falls, he finds Ben and Kami watching the Northern Lights. Surprised and relieved at Ben’s sense of self-sufficiency and courage, Harry and Kami both find a renewed sense of family, hope, and belief. They each realize that life isn’t always perfect, but facing it alone is not the answer. Inspired by Ben’s unwavering hope, they are embrace each other officially start the season (“Cue Christmas Reprise”).