On a rainy week of vacation, Harry finds a way to loosen his bossy big sister's grip on playtime scenarios.On Monday, the two go to Mars, "which looked a lot like the family room, except for the volcanoes." Because Harry sinks in quicksand, Clare eats his snack. On following days she not only gets to be race car driver, pirate queen, and school principal, but she appropriates his snacks again. When the penny finally drops, he starts stockpiling small treats in his pocketso that when skies clear and the children hit the jungle ("It looked a lot like the park, except for the vines and wild animals"), he's in a position to win concessions from his snackless sib: "I'll share. But I think the treasure is in a cave under a mountain." Says Clare, "Okay. But there's still a monster octopus in the cave." Staunton's tongue-in-cheek text displays both great respect for the imagination of children and affection for his characters. In simply drawn line-and-color illustrations, Song artfully blends ordinary household and playground details into adventuresome settings until at last steering the pair homeward past "prehistoric park-bench dinosaur skeletons" and deadly "squirrel sharks." The children are black-haired and light-skinned; the "Kimono dragons" they ride hint at Asian ancestry. A clever bit of conflict resolution, nonviolent and broadly applicable. (Picture book. 6-8) Copyright Kirkus Reviews, used with permission.