Hidden in the depths of Wealden Forest, a man hacks at the thick roots of a fallen oak tree. Drawn to a clearing by a strange and eerie song, he witnesses an incredible sight that sends a sudden, agonizing fear through his body. As he stumbles out of the forest into the bright light of a full moon, he hears a whistling noise close by. It is as if some ancient curse had been reawakened: The man meets with a violent end, killed instantly by a flint-headed spear.

The Sheriff of Tonbridge is happy to assume the Forest People did it, but Abbess Helewise believes a supernatural solution is too easy an answer. Fortunately, with King Richard Plantagenet halfway to Jerusalem on his latest crusade, Josse d'Acquin had returned to his new manor house in the Weald. Eager to investigate, Josse enters the forest himself -- and finds something that terrifies even him.

Another death soon follows, and Abbess Helewise, concerned about the involvement of two girls from Hawkenlye Abbey, joins Josse to discover what forces really lie in the mysterious darkness of the ancient forest.