The year is 1274, and, after years of bloodshed, peace reigns in the Middle East, in part due to the efforts of a mysterious group known as the Brethren. However, one of their number, Will Campbell, suspects that the Brethren have been betrayed. Their enemies are numerous and powerful: A cabal of ruthless Western merchants aims to reignite war in the Holy Land, in the hope that they can turn a profit—by means of a plan so scandalous that should they succeed the entire Muslim world will rise against the Christians in retaliation. Prince Edward—once a trusted member of the Brethren—has made a promise to the pope: He will take the Cross to Jerusalem and lead a new Crusade. War has come.

Meanwhile, in Egypt, Sultan Baybars is caught in a power struggle. His eldest son, and heir to the kingdom, has become involved in the dangerous designs of the insidious soothsayer, Khadir. While Baybars wants to take on the mighty Mongol empire, Khadir and others in the sultan’s court want to destroy the Christians once and for all. As the sultan’s son schemes against his own family, old scars of the Crusades are quickly uncovered and new wounds appear. To survive the escalating conflict and protect his family, Will must harness all his knowledge and courage. In a world of reckless greed and violence, Campbell may become the people’s last hope for peace.