Wishing for Trouble

Ben and Tim have always been told to "be careful what you wish for", but they don't know what this really means until one day Tim discovers a magic wishing ring - and a whole lot of trouble!
Before they know it, Ben and Tim and their cousins, Nick, Emmy and Lach, find themselves fighting for their lives - and a few other people's, too - in a besieged castle full of knights and swords and a rather bossy countess. But soon they realise that making wishes is not as easy as it sounds, and that they will have to be very clever indeed to get themselves out of this mess!