If you've been out and about in Swansea recently, chances are you may have seen one.
Books, sealed within a plastic bag, are being spotted everywhere across the city in recent weeks, to the delight of many young children and adults who have come across them on their travels.
They have been hidden in many secret locations, and come with the message: "Hello you are the lucky finder of this book. We hope you enjoy it.
"You can choose to take it away to read, pass it on to someone else to enjoy or leave it for someone else to find.
"Keep it as long you please. When you have finished with it remember to sign and date inside the cover and rehide it for someone else to enjoy - or you could hide a new book."
It is all thanks to a new group called 'Look For A Book Swansea', which aims to hide books for children and grown ups to find and read.
It was started by Bethan McGregor, who took inspiration from a similar scheme in West Cumbria, and decided to hide 28 of her own unwanted books for people to discover and enjoy.
A Facebook group was subsequently set up, and it snowballed, with an estimated 7,700 members joining and hiding their own books for others to discover.
"I saw a video on Facebook of people doing it up in West Cumbria of people hiding books, so I thought the same could be done here," Ms McGregor said.
"I started a page off a week Saturday telling people what it was all about, and then on the Sunday I hid 28 books around the city.
"I don't know how it has been so successful and how it has grown so quickly but people have fallen in love with the idea. We've just passed 7,700 members.
"I'm overwhelmed, that's the best way to put it. I'm loving seeing everybody's faces and everybody enjoying it. It's great seeing everybody joining in and doing it themselves.
"I work full time and would not be able to do it all myself. People have been in touch all over from Neath, Llanelli, the Isle of Man, and even in Perth in Australia supporting it.
"It's nice to see how excited everybody is about reading. It is such a simple thing, just hiding books that you won't read again to share them with others."
Ms McGregor, a local area co-ordinator for Swansea Council, said the activity was providing lots of social benefits.
"It is getting people outside and spending time with family and friends," the 34-year-old said.
"They're also reading for fun, not just because they have to in school and they are told they have to.
"There's an element of excitement going out and finding a book. Adults are enjoying taking part themselves too."
The group has had some difficulties, after a small number of books were discovered with their pages ripped.
"We've heard of about five or six cases, which when you consider we get 300 posts a day bare minimum on the Facebook page, you have to accept it's normal behaviour," Ms McGregor said.
"It is disappointing when it happens but you'll always get some who are not going to join in."
Discussing how long she thinks it can go on for, Ms McGregor added: "I think we have been lucky with the summer holidays, people are trying to find free activities to do. It will be nice if it carries on when the term time starts again. It is nice to see people getting excited about reading again."
Share your photos, clues or tell others about your book hunt on the Facebook group 'Swansea Look For A Book' .
