Simon and Malcolm think that their stay with Great Uncle Henry in Edinburgh is going to be incredibly boring. But then they discover the Martlet Box! With this discovery the two boys and their friend Robina are caught up in a battle between forces more powerful and fantastic than they could ever have imagined. The contents of the Martlet Box are the key to the battle. The children have it at the moment but others more powerful will go to any lengths to get it. With the help of the immortal Mrs Clarke and the strange knights, the three friends manage to keep the contents for a time. But when Robina is kidnapped they must go back to the past to rescue her and in doing so must make the most terrible decision of their lives. The Martlet Box is an exciting fantasy and mystery set in the narrow cobbled wynds and misty streets of Edinburgh.