Blue Penguin Classics paperback lost near Colby Library

I lost my blue Penguin Classics paperback edition of a mystery yesterday around 3pm near the Colby Public Library on Main Street. It's a 320-page paperback with a creased spine and a tiny red fox-shaped bookmark sticking out between chapters. The back cover has a faint coffee stain and there's my handwriting inside the front cover—a small note with my name. It was a gift from my grandmother and it means a lot to me; I really need it back as soon as possible.