Hermelin is a noticer. He is also a finder. The occupants of Offley Street are delighted when their missing items are found, but not so happy to learn that their brilliant detective is a mouse! What will happen to Hermelin? Will his talents go unrewarded?

Ratatouille meets Sherlock Holmes in this heartwarming story of mystery and adventure, acceptance and friendship, by the acclaimed creator of Traction Man and Toys in Space. Hermelin is a special little mouse. He was born in a box of cheese and lives in an attic at 33 Offley Street. He can read books and type notes on his typewriter. Most importantly, Hermelin can solve mysteries. And the people of Offley Street are in need of a detective! Again and again, Hermelin is on the case—the anonymous hero. But when his neighbors invite him to a thank-you party in his honor and find out who Hermelin really is—a MOUSE!—will he still be welcome on Offley Street?