Book excerpt: Surprise! Mad scientist Petty Potts is the new counselor at Josh and Danny's summer camp. And she just happens to be hiding some bottles of her extraordinary serum inside her raincoat. Now she can turn the boys into amphibians!Josh and Danny vow to stay away from Petty's S.W.I.T.C.H. formula, but when their new friend Charlie gets into trouble, they know there's only one option: find Petty and get hopping!