One day, Horton the elephant hears a cry for help coming from a speck of dust. Even though he can't see anyone on the speck, he decides to help it. Good thing since as it turns out, the speck of dust is home to the Whos, who live in their city of Whoville. Horton agrees to help protect the Whos and their home. Unfortunately for Horton, this gives him nothing but torment from his neighbors. They refuse to believe that anything could survive on the speck. Still, Horton stands by the motto that, "After all, a person is a person, no matter how small."

Title from container. This Blu-ray disc will not play in standard DVD players. Based on the book by Dr. Seuss. Special features: Audio commentary with directors Jimmy Hayward and Steve Martino; Audio commentary with actors Jim Carrey and Steve Carell; "Ice age" short: Surviving Sid; Watch Horton hears a Who! with a Who; Beyond animation; "The voice of Horton: Jim Carrey" featurette; "That's one big elephant" featurette; "The genesis of Katie" featurette; "Your world is changing, too!" featurette; "How does Horton hear?" featurette; "A person is a person: practical life lessons" featurette; "Is it Seuss?" featurette; 13 deleted scenes with an introduction with directors; 23 animation screen tests: introduction to animation tests with animator Nick Bruno; "We are here!" game.