When their sister, Jenny, is accidentally turned into a crane fly by Petty Potts' SWITCH spray, twins Josh and Danny must transform themselves, as well, and rescue her before she burns her legs off.
At summer camp, twins Josh and Danny and their new friend, Charlie, still have frog's legs from when "camp counselor" Petty Potts sprayed them with her new AMPHISWITCH, but a second attempt to restore them turns them into newts, instead.
An intruder at mad scientist's Petty Potts' house interrupts her latest experiment, trying REPTOSWITCH on twins Josh and Danny, and when they return home they find a package that sends them on a mysterious quest.
Twins Danny and Josh reveal to neighbor Petty Potts that they have been on a quest to find marbles containing secret code and soon find themselves--as geckos--in her new secret laboratory within the very pink Princessland.
Twins Danny and Josh are having a miserable time at camp when mad scientist Petty Potts arrives, armed with her new AMPHISWITCH formula, just in time to get another camper out of trouble.
While on vacation with their parents in Cornwall, twins Danny and Josh follow clues to another marble but find themselves trapped by the tide on a rocky island and the only way back is to use some pilfered REPTOSWITCH.
At the zoo, twins Josh and Danny willingly try out Petty Pott's REPTOSWITCH formula and enjoy being snakes until they are spotted by a group of girls on a field trip, including their camp friend, Charlie.
When Petty Potts disappears, twins Danny and Josh search her secret laboratory and house, where they find an irresistible bottle of S.W.I.T.C.H. spray, and later they find themselves on a live television talk show.
While seeking their lost dog, Piddle, twins Josh and Danny encounter their next-door neighbor, Petty Potts, a mad scientist whose SWITCH spray accidentally turns them into spiders.
After accidentally drinking some of mad scientist Petty Pott's SWITCH potion while at school, twins Josh and Danny become grasshoppers and this time they may not change back without help.
