The Flynn-Fletcher Family go on a vacation to Hawaii. While they are there, Phineas and Ferb make living sea creatures and Candace find a lava necklace of bad luck. Meanwhile, Doofenshmirtz creates a De-Evolution-inator and Perry and him get stranded on a island.

Phineas and Ferb head to the Tri-State area's annual sci-fi/comic book convention to meet their hero, special effects guru Clive Addison. Their plan gets sidetracked when they're swept into a duel between fantasy fans and sci-fi geeks. Meanwhile, Candace tries to keep secret that she's a fan of Ducky Mo-Mo, another convention staple. Across the convention hall, Dr. Doofenshmirtz has taken television executive Jeff McGarland hostage so he can pitch him a show he's developed, Doof ‘N' Puss.