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 safe place for the speck or the speck will be destroyed.

So Horton Is traveling up a hill to a safe place for the speck. But the Sour Kangaroo 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...