When Sir Galahad arrives in Camelot to fulfill his destiny, the presence of Lancelot’s illegitimate son disturbs Queen Guinevere. But the young knight’s vision of the Holy Grail at Pentecost inspires the entire fellowship of the Round Table to rush off in quest of Christendom’s most holy relic.
But as the quest gets under way, Sir Gawain and Sir Ywain are both seriously wounded, and Sir Safer and Sir Ironside are killed by a mysterious White Knight, who claims to impose rules upon the quest. And this is just the beginning. When knight after knight turns up dead or gravely wounded, sometimes at the hands of their fellow knights, Gildas and Merlin begin to suspect some sinister force behind the Grail madness, bent on nothing less than the destruction of Arthur and his table. They begin their own quest: to find the conspirator or conspirators behind the deaths of Arthur’s good knights. Is it the king’s enigmatic sister Morgan la Fay? Could it be Arthur’s own bastard Sir Mordred, hoping to seize the throne for himself? Or is it some darker, older grievance against the king that cries out for vengeance? Before Merlin and Gildas are through, they are destined to lose a number of close comrades, and Gildas finds himself finally forced to prove his worth as a potential knight, facing down an armed and mounted enemy with nothing less than the lives of Merlin and his master Sir Gareth at stake.