Zero and Zelda Schall, twin rat kits, have spent their lives in Sanctuary, a sheltered community in the Copperbright Kingdom—and one of the few safe places for their kind. Zero is enraptured by stories of magic and fantasy. Zelda craves adventure. Their parents—former boy hero Nathan and retired master thief Zoya—don’t want them following in their dangerous footsteps.

Sir Huntington Phocks, an aristocratic fox with dreams of claiming the Copperbright Crown for himself, has other ideas—and wants Sanctuary destroyed.

After his trio of frog acrobat assassins leave their father grievously wounded and kidnap their mother, the twins must become the heroes that Sanctuary needs. Zero takes his father’s place in the court of Copperbright Queen Gloriana, a world of skullduggery and intrigue, of vole spymasters and newt occultists, where secrets hold power and every paw clasps a hidden blade. Zelda pursues her mother’s kidnappers to the island kingdom of Sakura—a land of feuding lords, brutal warriors, haunted grasslands, and a roguish Red Panda ronin who will become her friend and protector.

Zelda and Zero will find more unlikely allies—rebel bats, axolotl warriors, and a blind gecko gambler—in their quest to uncover and stop Phocks’ twisted scheme to take Queen Gloriana’s throne and save their parents and their homeland. Will they grow up fast enough to survive in a world that accepts no weakness from small creatures—and offers no refuge for rats?