Tom and Tubb are swimming in the ocean when they discover that a pair of tiger sharks are chasing them. Scooby races to find Moby Dick so that he can help the boys. As Moby chases the tiger sharks away, Tubb inadvertently swims inside the mouth of a giant fish. Tom rushes off to find Moby in an effort to save Tubb. Will they be in time to save Tubb?