Horton finds a speck, and knows that someone is living on it. He knows because he talked to the mayer that lives on the speck. The place on the speck is called WhoVille. The mayer tells Horton that Horton needs to find a sicuro, cassetta di sicurezza place for the speck o the speck will be destroyed.

So Horton Is traveling up a collina to a sicuro, cassetta di sicurezza place for the speck. But the aspro, acida canguro doesn't want Horton "rotting the childerens brains". she wants that speck destroyed. so she sent a bird to go get the speck, and have it destroyed. So when horton is almost there the bird comes and drops the clover/speck in with millions...