The year is 1274 and a tentative truce holds in the Kingdom of Jerusalem, a truce brought about by the secret efforts of the Brethren, a secret organization within the Knights Templar devoted to the reconciliation of Judaism, Christianity and Islam and peace in the Middle East. Unfortunately, the peace becomes a problem for a sinister cabal of merchants of Acre: their shipyards stand idle, for orders from princes and kings dry up. Their foundries no longer turn out armor for armies preparing for battle, and the slave trade slows to a crawl. Their solution? An act so audacious that it is sure to result in cataclysmic war between Muslims and Christians, filling the merchant's coffers. But the scheming merchants are not the only threat to peace.

Will Campbell, a knight in the Templars, learns that Prince Edward of England is contemplating a new crusade. Because Edward is one of the Brethren, Campbell is upset by the possibility that the English prince would betray the goals of the Brethren by trying to stir up a crusade.

In Cairo, a meddling soothsayer uses the heir of Sultan Baybar, Baraka, a young man resentful of a father who will not take him seriously, to try and start a war with the Christians by having the young heir order an attack on a Christian settlement.

Many forces are at play, posing serious challenges to any hope of continued peace. Campbell's story interweaves with the conspiracy when he is promoted to commander after saving the grand master from an assassination attempt. His investigation into who was behind the attack turns up only a mysterious reference to The Black Stone, spoken in the dying breath of Guido, one of the conspirators, before he has a chance to reveal more. Guido's untimely death also becomes a tip for Campbell that something isn't quite right: Angelo's explanation for why he killed the merchant before Campbell could further question him does not ring true, and that evasiveness is what makes Campbell suspicious.

Those suspicions are further fanned by the dismissive tone the grand master takes to the entire incident, buying completely into the unlikely explanation that the merchant wanted to have the grand master killed for a shipping contract. With the matter seemingly closed, the grand master sends Campbell on a mission to deliver a scroll with highly sensitive information to Kaysan, a Shia mercenary who works also as Templar spy. With the perplexing words of the dying merchant giving Campbell's imagination no rest, he seals furtive glimpses into the scroll that he is charged to deliver to Kaysan. The contents is indecipherable, being of no specific language but in code. Only when the comrades of Kaysan utter the mysterious phrase "The Black Stone" do Campbell's suspicions about the grand master prove not completely unfounded, and he goes on a secret mission to decode the secret message. Eventually Campbell learns the meaning of the words, and the story kicks into overdrive of suspense.

The plot moves swiftly despite complexities and complications exploding on each page. The many conflicts, deceptions, and plots that the characters engage in are skillfully handled, generating even more tension and interest as the story progresses. Young accomplishes this through the use of dramatic irony, often keeping characters in the dark about the plots and pending treachery of others but giving the reader a vista into the complicated machinery of human heart and its conflicting motives. Yet there is more to Crusade than just a good plot.

The characters are vivid and alive, moved toward their destinies by understandable human desires. They are complex, human, and deeply flawed, driven as they are by their flaws to commit unspeakable betrayals and barbarities for the sake of ideals, hoping to achieve some good with their questionable acts. Indeed, even the most despicable of them are driven by a notion of good, acting always for the sake of some higher good — peace, kingdom-building, and truth as they see it.

Crusade crafts a richly detailed world of the Kingdom of Jerusalem, presenting the complicated tapestry of conflicting interests, betrayals, and tenuous alliances in an unstable world with an astute regard of the political realities. Thought it may seem to reflect a world long vanished, Crusade is a mirror of our own times, an era of conflicts and new dangers coming from non-state actors, failed states, and religious warfare.

• The Fall of the Templars
• Brethren