Red hardcover mystery novel with dog-eared pages

I lost my red hardcover mystery novel yesterday around 3pm. I was in Waterstones on Union Street in Aberdeen, sitting in the cafe area when I think I left it on a table after finishing a chapter. It's a Penguin Books edition with a blue ribbon bookmark peeking out from the pages. The cover has a small dent along the bottom-right corner and a coffee stain on the inside front page. It was a gift from my grandmother and it means a lot to me, so I'm hoping someone picked it up. If you found it, please get in touch.