Characters

• Celian d'Arestide - The player character, Celian is noble, chivalrous knight who fights to preserve his order amid the Inquisition. Unlike many of his contemporaries, Celian received a formal education in addition to his combat training. Due to him falling from a tower in his past, Celian has lost all of his memories prior to adulthood.
• Marie d'Ibelin - The granddaughter of Guy d'Ibelin, Marie was raised in Saracen traditions. She joins Celian after being branded a heretic by the Inquisitors. Taught to fight and defend herself at an early age, she utilizes twin daggers in combat.
• Roland de Saint-Omer - A senior member of the Templar order who fought alongside Celian in several campaigns in the East.
• Lady Isabelle - a French messenger sent by Phillip IV, you later find out that she is trying to destroy the templar order and she masks her goals to Celian and his friends.
• Wilhelm of Beaujeau - The Grand Master of the Templar Order and Celian's longtime mentor. He is described as a wise leader who is physically robust despite his advanced age.
• Phillip IV - The King of France, and one of the primary antagonists. He betrays the Templar Order and allies himself with the Inquisition.
• The Byzantine - A secondary antagonist introduced in the Arena DLC pack. He lives in a fortified castle with a large arena, and forces his prisoners to engage in gladiatorial combat.

Story

In 1291, the Crusades, as well as the Kingdom of Jerusalem, are coming to an end. Acre, the last Christian city in the Holy Land, is under siege and about to fall into Mamluk hands.

Celian and Roland, two Templar knights, have just arrived in Cyprus in order to talk to the Templar Grandmaster, seeking advice in their quest for the Holy Grail. Upon their arrival, they find that the island is being attacked by Muslim warriors, and they hurry to protect it. In doing so, they encounter a kidnapped messenger from Guy d'Ibelin, who tells them that the Grandmaster's daughter, Marie d'Ibelin, is being held prisoner by the Inquisition.

After consulting their Grandmaster, the two go to an undetermined location in Europe, where they discover that the Inquisition (led by a shadowy agent named Isaiah) is plotting something of monumental proportions. They release Marie, but Roland is left behind during their escape, presumably killed – thus, Marie becomes Celian's partner for most of the subsequent game.

Celian and Marie continue their quest for the Grail, fighting a great deal of Muslim enemies in the process and helping those in need – even though the idea of helping always comes from Celian and is criticized by Marie, who remarks that they are wasting time doing so. At some point, the pair discovers that Guy d'Ibelin is also dead, and that the Holy Land is lost for good. They finally find the Holy Grail Temple, but they learn that it was emptied long ago. Inside the temple, they find a dying Templar who mistakes Celian for the Grandmaster. Running out of options, they decide to go to France in order to get some advice from the Grandmaster and the main body of the Order.

They arrive in France in 1307, the year in which King Philip IV and Pope Clement V start their accusations against the Templar Order. Both heroes fall into the Inquisition's trap; but just when they are about to be imprisoned, they find Roland, who has not been killed but instead was tortured and then pledged his allegiance to the anti-Templar movement, therefore becoming its Black Knight.

However, Roland's friendship to Celian turns out to be much stronger than his newly found allegiance, so he helps his friend reach an escape port through the forest, where Celian is reunited with Marie. From that point on, Roland tells them they are on their own, and so they depart for a fortified Templar stronghold, where they intend to join forces with the Grandmaster to fight back against the French army.

The Grandmaster reveals that Celian is in fact Hugues de Payens, the founder of the Templar Order. His memory loss was a side effect due to an assassination attempt by the current Grandmaster himself, because he had hidden the Grail, which was responsible for prolonging the lives of the nine founders far beyond the natural lifespan of a normal human being. After three of the original nine died (probably due to internal power struggles), Hugues realized that the Grail was dangerous, and so he took it away and hid it. But the Grandmaster – who is himself one of the original nine – wanted the Grail back; he thus took advantage from Hugues' memory loss and gave him the task of finding the cup, in hopes that something inside him would lead him straight to it.

After the plot twist, the player realizes that the true enemy is actually the Templar Order, who becomes the main antagonist from now on. By remembering his true identity, Celian (aka Hugues) also concludes that his castle would be just the place where he would hide something he didn't want anyone to ever find.

In the end, the player defeats both the Grandmaster and Isaiah (the agent from the Inquisition), and he is given a choice to use the Grail or destroy it. This affects only the final narration, describing either immortal guardians or humanity free to make its own decisions.