Johnny Boo has been eating a little too much ice cream, and now his muscles have gotten all floppy and droopy. Meanwhile, the Ice Cream Monster has changed his ways and now has big strong muscles, thanks to his new favorite food: apples! Terribly embarrassed by his own puny muscles, Johnny Boo sets out on a quest to find some happy apples that can give him strong happy muscles. But it won't be easy - especially if the Ice Cream Monster mistakes him for a delicious ice cream cone!