Gwyneth and Hereward Mason witness a marvellous discovery deep below the Abbey courtyard. Could this cross found in the oak-tree coffin really prove that these are the bones of the legendary King Arthur? Disaster strikes, the relics have gone! Gwyneth and Hereward must find them in order to save the Abbey's fortunes. A sinister priest, a mysterious hermit, and a sneakly merchant all seem to have a part to play in the disappearance.