Inside a snowflake, high atop Mt. Crumpit, just north of town, a certain cave-dwelling curmudgeon peers down on the Christmas-adoring Whos of Whoville as they make their frantic Yuletide preparations. And this isn't your run-of-the-mill sourpuss. This is the Grinch (Jim Carrey), and he is positively sick of those nog-sucking cheermongers. Christmas is back and the Grinch plans to do something about this annoyingly-happy holiday ... once and for all.

Until he encounters little Cindy Lou Who (Taylor Momsen) who takes matters into her own hands, trying to find out everything she can about the Grinch: Who he is, why he doesn't like Christmas and why he is held in such utter contempt. Her innocent questions turn Whoville upside down, but ultimately, these two kindred spirits-one searching for just one thing meaningful from the yuletide holiday, and the other unearthing a part of his soul long ago buried and forgotten-will come together, and collectively learn the true meaning of Christmas.