Following Arthur's miraculous healing by Christ's cup from an apparently fatal wound, Arthur sets his heart upon establishing a shrine to the Grail as a symbol of the Summer Realm he has introduced to Britain. But in this account by Gwalchavad (Galahad), Myrddin's (Merlin) old enemy Morgian concocts a devastating betrayal by one of Arthur's dearest companions. Arthur's dream is soon in tatters and the newly won peace and promised prosperity in Britain are threatened with great evil.