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.
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.
At the zoo, twins Josh and Danny willingly try out Petty Pott's new REPTOSWITCH formula and enjoy being snakes until they are spotted by a group of girls on a field trip, including their camp friend, Charlie.