A thrilling, mysterious and very, very funny new adventure from the award-winning author of EINSTEIN THE PENGUIN, with brilliant illustrations from bestseller David Tazzyman.

Cecily Sawyer has spent the evening in the attic, training her pet mouse, Mrs Maple Syrup - an unusually intelligent mouse, in Cecily's opinion - when her parents disappear.

Luckily, Cecily is more than ready to investigate such a thing. She has wanted to be a spy her whole life, and has all the spy handbooks, manuals and code-cracking kits a girl could need.

But soon, Cecily discovers several very strange things in her city. She's not the only spy out there - far from it, in fact. And Mrs Maple Syrup is not the only unusually intelligent mouse...