In this sweet-natured story, when three unnamed mouse brothers discover a key in the woods, they take turns guessing what it might open. The "littlest" mouse, who first spotted the key, thinking it was a "little piece of sun that's fallen onto the ground," imagines that it unlocks a chest of pirate treasure. After some digging, the mice find a buried chest--pretty impressive!--but the key doesn't open it. The "middle-sized" mouse guesses it must open a castle, while the "biggest" one thinks it's the key to happiness. Aliaga (Dorothy: A Different Kind of Friend) uses direct sentences and repeating phrases to give the story a gentle cadence that's well suited to readalouds. Padron's marbled and canvas textures create an almost-three-dimensional world for the mice to explore, one with chunks of cheese tucked into tree branches and keyholes in everything from rocks to giant apples. A tidy ending reveals where the key belongs (hint: Mom looks relieved to see it) and proves all three brothers' guesses to be right, in a way (...) Publisher's Weekly, May 2016
