In the city of Whoville, everyone celebrates Christmas with much happiness and joy, with the exception of the cynical and misanthropic Grinch (Jim Carrey), who despises Christmas and the Whos with great wrath and occasionally pulls dangerous and harmful practical jokes on them. As a result, no one likes or cares for him.
Cindy Lou (Taylor Momsen), an 8-year-old girl, believes everyone is missing the point about Christmas. After finding him messing up the mail in the post office, Cindy Lou becomes aware of the Grinch's existence, and starts to create interest in the Grinch and his history, asking everyone what they know about him, and soon discovers that he has a tragic past.