Adapting the slim and charmingly quaint stories of Dr. Seuss into feature-length films has always been a dicey proposition, which makes the success of Horton Hears a Who all the sweeter. This loving tribute to Seuss—a step up from the team behind Ice Age—does pretty much everything right. Jim Carrey voices the elephant Horton, who finds himself the godlike savior of a microscopic civilization that's no bigger than a speck on a clover. Steve Carell plays the mayor of said civilization, Whoville, with his usual limber charm. The story remains a subversive head trip for kids about our size in the universe, and reimagined as a gently rollicking action comedy, it only rarely goes for a gauche laugh over Seussian purity.