One night, two newly-made paper mice separately explore a dark house, finding each other along the way and discovering a shared love of adventure.

"Eleven-year-old Avery Lee loves living in Hickory Valley, Maryland. She loves her neighborhood, school, and the end-of-summer fair she always goes to with her two best friends. But she's tired of feeling squished by her six siblings! They're noisy and chaotic and the younger kids love her a little too much. All Avery wants is her own room -- her own space to be alone and make art. So she's furious when Theo, her grumpy older brother, gets his own...