Summary
Highlights
Johnny and his family are at the beach early. Johnny wishes he could breathe underwater to collect cans, sparking an idea that his genius sisters might help with.
Johnny's sisters, Susan and Mary, want to get a perfect tan to impress Gil. Johnny also wants gills to collect more cans. The sisters agree to help Johnny in exchange for his help with their tan.
Johnny's sisters use an 'aqua conversion process' to turn him into a fish. Underwater, Johnny discovers toxic waste and a secret glass dome civilization. Meanwhile, Susan and Mary experiment with a hyperkinetic tanning spray, which goes wrong, turning Susan's skin various colors.
Gil encounters Susan, who has kaleidoscopic skin, and finds her 'super cool'. Johnny is chased by angry sea creatures after disturbing their habitat. The sisters then transform the creatures into land-dwelling beings.
The land-dwelling mutant sea creatures cause chaos. Dukey, Johnny's dog, helps stop the mutant eel at the beach club. Johnny helps save Gil from the land shark. The trio then works together to deal with the octopus.
The sea creatures from the glass dome civilization confront Johnny's parents about the destruction caused by 'flame-headed fish boy.' Later, Johnny's sisters introduce their new invention, a DNA converter that can transform subjects into replicas of given hair samples.
The sisters also unveil the Amazing Turbo Action Backpack (ATAB), which responds to voice commands. They plan to present it at a college fair for a scholarship. Johnny wants the backpack, but his sisters refuse, citing his destructive tendencies.
Johnny complains about his 'baby barf' colored backpack, which his father made him use. After being teased at school, Johnny decides to sneak into the lab and take the ATAB.
Johnny uses the ATAB to shrink his books, get to school quickly, ditch French class, play video games, and even deal with bullies, impressing his classmates.
Bling Bling Boy steals the ATAB and demands that Susan Test meet him for a romantic dinner at his estate at 6:00 PM, captured on a DVD message.
Since Susan and Mary are at the college presentation, Johnny uses the DNA converter to transform Dukey into a likeness of Susan, sending him to Bling Bling Boy's estate to stall him while Johnny retrieves the backpack.
At the college fair, Susan and Mary try to present their ATAB, unaware it's gone. At Bling Bling Boy's, Dukey (as Susan) causes a distraction. Bling Bling Boy eventually realizes he's been tricked. Johnny retrieves the backpack, and they escape Bling Bling Boy's attacking shark-bots.
Johnny blasts them to the science fair, where his sisters are presenting. The college board members are unimpressed by the ATAB's complexity but are captivated by Johnny's 'baby barf' backpack, praising its retro and simple design, declaring it the new cool.