Nanami Kosaki loves reading. The local library has become a home from home. Books are her friends. When Nanami notices that some of her favourite books are disappearing from the library shelves, she becomes suspicious of a man in a grey suit whose furtive behaviour doesn’t feel right. Should she follow him to see what he’s up to? It wouldn’t be dangerous . . . would it? When a smart-talking tabby cat called Tiger appears and issues a grave warning about how dangerous that would be, they decide to team up and investigate. Where have all the books gone? And can the unlikely duo overcome the challenges ahead?