The fretful Marlin and his young son Nemo become separated from each other in the Great Barrier Reef. Nemo, a clown fish, is unexpectedly taken from his home and thrust into a fish tank in a dentist's office overlooking Sydney Harbor. Buoyed by the companionship of a friendly fish named Dory, Marlin embarks on a dangerous trek and finds himself the unlikely hero.

The adventure begins when Tom and Jerry happen upon a mysterious glowing egg. Little do they know, this egg was stolen from a very large fire breathing dragon. In short time, baby Puffy hatches from his egg and takes Tom as his mommy.