On Christmas Eve, a young boy who is starting to doubt the existence of Santa Claus lies awake in his bed, eagerly listening for the sound of sleigh bells. Suddenly, his house trembles as a mysterious train appears outside his window. The train's conductor invites him aboard what he calls the Polar Express, a magical train bound for the North Pole. Intrigued by the prospect of meeting Santa Claus, the boy boards the train, embarking on a journey of self-discovery and wonder. Aboard the train, he meets other children, each with their own beliefs and stories, including a spirited girl who believes strongly in the spirit of Christmas, a know-it-all boy who flaunts his knowledge, and a shy boy from a poor background who longs to believe in something greater.

Throughout their adventure to the North Pole, the children encounter a series of astonishing and mystical experiences. The Polar Express races through treacherous territories, including steep mountains and ice-covered tracks. The boy and his newfound friends face various challenges that test their courage, trust, and perceptions of reality. Their camaraderie grows as they share hot chocolate, sing carols, and navigate their way through the picturesque yet perilous landscapes. These shared experiences bond the children as they learn important lessons about belief, friendship, and the enduring magic of Christmas, all while they draw ever closer to their ultimate destination where they are promised a meeting with Santa Claus himself.