“ ‘Well, boys,’ I say in a voice an octave deeper than usual. ‘we’re all alone in the big, big, big, big world for the first time in our short, short, short, boring lives. Now is the time to gather up every ounce of courage, guts, strength, and pocket change.’ ” So Brook, a guinea pig, addresses his two former cagemates Allen and Leone after they find themselves set free in New York’s Central Park. It takes but a moment, however, to realize that the great outdoors is a far chancier place than The Natural Pet, with its free food, clean water and bubble baths—and so begins an epic odyssey to find their way back to the store, though giant pigeons, rushing pedestrians, busy streets and other hazards bar the way. Captain Underpants–style, Proimos and Rheingold mix well-spaced lines of text and black-and-white cartoon scenes with dialogue balloons to relate this madcap tale, taking their three reluctant adventurers through encounters with helpful roaches and other wildlife, then leaving them at episode’s end trapped aboard a departing subway train. Even readers with short attention spans will want to know what happens next. Stay tuned. (Fiction. 8-10)