Doofenshmirtz uses his Un-Fossilize-Inator to bring back a Megalodon Shark. After a bounty is set for it, Phineas, Ferb and the gang all head out to catch it, but they find themselves working with a new, unexpected ally: Dirty Matt! Meanwhile, Perry must stop Doofenshmirtz from making another big mistake by reviving a Dinosaur army.