If someone dares you to spend the night in a haunted castle, would you do it? Of course, you can only get to this particular castle by going to the town of Beaumaris. The town can be found on the island of Anglesey. The island is part of the country of Wales. Beaumaris Castle, though never finished, was built by 1296. Seven hundred years later, in 1996, twelve-year-old Gwyn makes this tiny town his home.

One day, Gwyn's new friends reveal that Beaumaris Castle is haunted. Gwyn declares, “There is no such thing as a ghost!” To prove him wrong, his friends dare him to spend the night inside one of the guard rooms. Gwyn agrees. What he sees finally puts to rest a 700-year-old question: How and why did the king's archer die?