Recruited as a youth by King Louis IX to serve in his private royal guard, Griffin d''Varden is instead invested into the Knights Templar. Within months of his arrival in Paris, he is sent to the Holy Land.

Far from his beloved home in the French Alps, Griffin is trained as an Assassin for the Brotherhood and the King. Ashamed of what he has become, he loses contact with those he has left behind.

Catherine d'Isere has adored Griffin all her life. When he leaves home to fulfill his dream of becoming a renown knight of the realm, she expects him to return once he has made a name for himself. When he doesn't, she sets out to find what happened to him. Secretly, she follows her father and twin brother on crusade to Egypt.

Griffin soon learns of her arrival. Stationed in the Christian occupied city of Damietta, at the mouth of the Nile delta, he avoids her and her family. When the King and his army march on Cairo, Catherine's brother and father accompany him.

Within weeks, the crusade turns disastrous. King Louis and all of his men are captured halfway to their destination and held for ransom in Cairo prisons. Griffin ends up in a prison cell with his fallen comrades. He is given a chance by the traitorous sultana and his Mameluk captors to free himself and Catherine's father and brother if he agrees to assassinate the newest sultan.

When he arrives at the Egyptian palace, he discovers Catherine has been captured by bounty hunters and is being held by the sultan. He carries out his mission and kills the sultan before Catherine's eyes, his only consolation being that she doesn't recognize him in his Assassin's garb.

Once they escape Cairo, that changes. Fleeing across the desert to Damietta, Catherine finally discovers his identity, but not the secret he diligently keeps from her.

As soon as the King is ransomed and surrenders the Egyptian coastal city, Catherine and her family escape to Acre with the royal family aboard a Templar vessel. Catherine remains in the Holy Land as one of the queen's closest friends and ladies-in-waiting.

During her stay in Outremer, her relationship with Griffin grows into a dangerous affair that jeopardizes his secret and his status in the Order. When Catherine finally learns what he has been doing for the King and the Brotherhood, her reaction is unexpected. Griffin insists that they end their liaison. The burden of what he has become clashes with his honor. He insists Catherine go home with her family and the King when they eventually depart the Holy Land.

Catherine is heartbroken and angry, and she carries a secret home with her that she refuses to share with her family and Griffin. Tormented by her rejection of him, Griffin must decide how he will reconcile with a past that has given him nothing but grief and regret.