Sir Geoffrey Mappestone and his loyal friend Roger seek passage on one of the many ships due to sail to Normandy and then on to the Holy Land. The two knights have been away from the Crusade too long, and are itching to get back to the action. But peculiar things have been happening in the harbour town, and it soon becomes evident that someone is trying to keep Geoffrey and Roger from boarding one of the ships. When Geoffrey's dim-witted servant is killed by a deadly arrow that was clearly meant for the knight himself, Sir Geoffrey's fury is such that he would do anything to find the murderer. But then Ranulf Flambard - who is not only the Bishop of Durham and an escapee from the Tower of London, but also happens to be Roger's father - arrives in Southampton with an errand for his son to perform. Much against Geoffrey's better judgement, the pair set off for the northern town of Durham, where a magnificent cathedral is being built at Flambard's behest.

As yet more arrows fly Geoffrey's way, the knight begins to realize that none of these events are random, and it is down to him to discover the connection between the two towns, Bishop Flambard and a handful of red-stained arrows.