Two quarrelsome but close mice suffer narrow squeaks in this tongue-in-cheek series opener. Looking for a new home as safe and well-stocked as the deli where they were born, sibs Molly and Jake find an odd “store” with playground equipment in the “parking lot.” While plump Jake goes off to look for another entrance, Molly wiggles through a crack in the wall, and soon finds herself being squired around a dark third-grade classroom by genial Gino the gerbil, ghost of a recently deceased class pet. Meanwhile, what with all-too-close encounters with Big Gray the cat (“I always get my mouse”) and a barn owl named Hooter, Jake’s having a much harder time of it. Asch switches scenes in alternate chapters, ending Jake’s with cliffhangers and lacing Molly’s with happy wonder as she meets other (living) class mascots and learns how to use another kind of mouse to surf the Internet. Ultimately, Jake and Big Gray enter the room at nearly the same time, setting the stage for a hilariously different game of cat-and-mouse. With Kanzler’s charming sketches providing a mouse’s-eye view, events hurtle along to a doubtless temporary standoff that sees Big Gray hauled outside by the teacher, while Jake and Molly, in a comfy hideout behind the class’s walls, peer out into a once-limited world considerably expanded by new thoughts and experiences. Young readers will be eager to see what develops in future episodes. (Fiction. 8-10)