It's the Harbor Days Festival and Phineas and Ferb celebrate by making a mechanical version of the historical shark of Danville Harbor. Seeing what the boys are up to, Candace enlists Captain Squint to track down and capture the elusive shark. A crazy water chase ensues. Meanwhile, Doofenshmirtz invents the Salt Water Taffy-inator to give cavities to every kid in the Tri-State Area.