The book is now widely considered to be a classic Christmas story for young children. It was praised for its detailed illustrations and calm, relaxing storyline. In 1986, it was awarded the Caldecott Medal for children's literature. The book is set partially in Grand Rapids, Michigan, the author's home town. It is published in both soft and hard-copies.
On Christmas Eve, a young boy is hoping for belief in the true spirit of Christmas. Suddenly, a fantasy magic train called the Polar Express pulls up in front of his house. He is invited aboard by the train's conductor to journey to the North Pole.
The train passes through villages and forests until it reaches the North Pole. There, the boy is handpicked by Santa Claus to receive "The First Gift Of Christmas". Realizing that he could choose anything in the world, the boy asks for the beautiful-sounding silver bell (that only believers can hear). The boy places the bell in the pocket of his robe and all the children watch as Santa takes off for his yearly delivery.
As the train leaves, the Hero Boy discovers the pocket of his robe torn and the bell missing. One child suggests they go back outside to find it, but it is too late. He is saddened by the loss of his bell. When the train arrives at Hero Boy's house, he says goodbye and waves from the doorway of his home as the train pulls away. On Christmas morning, his sister finds a small present hidden behind the tree after all the others have been unwrapped. The Boy opens the present and discovers that it is the bell, which Santa had found on the seat of his sleigh. When the boy rings the bell, both he and his sister marvel at the beautiful sound; but because their parents no longer believe in Santa Claus or Christmas, they do not hear it. The book ends with this last line:
"At one time, most of my friends could hear the bell, but as years passed, it fell silent for all of them. Even Sarah found one Christmas that she could no longer hear its sweet sound. Though I've grown old, the bell still rings for me, as it does for all who truly believe."