Gilbert de Rideford, a Templar known to John from the crusade, arrives in Devon claiming to possess information that could damage the military order and shake Christian authority. Pursued by men determined to silence him, Gilbert asks John to help him escape before the secret is recovered.
The trail carries John from Exeter into a struggle involving churchmen, royal interests and the pirates occupying Lundy Island. To discover why Gilbert is being hunted, he must survive a dangerous mission across the Bristol Channel and decide whether the alleged revelation is genuine, heretical or a weapon in a political contest.