In the local library, which I visit once a week, they have a Mystery Book on the Issues counter. It is hidden inside a plain white A4 envelope. On four consecutive Saturdays, I have been able to resist. This week I cracked. I had to have it. They wouldn't let me have the Mystery Book on the counter. Underneath the desk, there is a pile of plain white envelopes. I get the one on the top, and leave the library without opening it. I'm expecting a middle-brow novel. It would be great to have a handbook on gyro-copter mechanics, or a guide to the sacrificial customs of Ancient Mesopatamia. However, I can't quite believe a library will let its