Henry accepts Merlin's mysterious challenge on his eleventh birthday, and it leads him and his dog to a magical adventure in the colourful but menacing world of the Knights of the Round Table. The dangers of life in the Dark Ages are the least of Henry's problems as he is faced with the strange beliefs, diet, table manners, fashion, humour and stinking bathroom facilities at King Arthur's court. Henry is sent on a perilous quest to recover a fabulous lost treasure from an evil foe. He must do everything right or be trapped in the past for ever. Can he complete his secret mission and find the way home?