In the jungle of Nool, the elephant Horton hears a voice in a speck; he uses a clover to rescue the speck of dust and he makes contact with the Mayor of Whoville. Horton discovers that in that tiny speck there is a city crowded with creatures and he decides to leave Whoville in a safe place. However, the evil Kangaroo does not believe Horton's story and thinks he's dangerous for the children of Nool, making them believe in what they can not see, hear or feel, and incites the animals against Horton.

Jim Carrey’s second movie based on a Dr. Seuss story. The first was (How the Grinch Stole Christmas (2000)). Both stories have Whos in them.

Horton:
There's a tiny person on that speck that needs my help!

Revealing mistakes: When Vlad drops the clover, he drops it straight down. Horton shouldn't have had to be halfway out in the field looking for the clover with the speck, as the movie shows. Also, the clover with the speck wasn't growing, so Horton shouldn't have had to pick the clover.

Written by Kevin Cronin
Performed by Jim Carrey, Steve Carell, Carol Burnett, Will Arnett,
Seth Rogen and Dan Fogler