How the Grinch Stole Christmas tells the story of the hateful and bitter Grinch, a Christmas-hating creature who lives in a cave on Mt. Crumpit above a small town called Who-ville. While nobody knows why the Grinch detests Christmas so much, the narrator posits that it is because his heart is two sizes too small.
By contrast, the Whos of Who-ville are kind-hearted creatures who absolutely love Christmas. The festive season is their favorite time of year, and they have very large and noisy celebrations in their town. As the Grinch becomes more and more annoyed with the noise, he devises a plan to "steal" Christmas: he dresses up as Santa Claus and sneaks into the homes of the Whos, taking their presents, food, and even their Christmas trees. In the middle of his scheme, he meets a little girl named Cindy-Lou Who, who shows the Grinch compassion and kindness.
As the Grinch attempts to dump all of his stolen goods over the top of Mt. Crumpit, he hears the Whos below singing. Shocked by their joy despite not having any gifts, the Grinch realizes that Christmas is not about material possessions but about community, kindness, and love. His heart immediately grows three sizes, and he returns to Who-ville to deliver all the presents he stole. At the end of the story, the Grinch is the one who carves the roast beast at the giant Who feast.