The Kingdom of Heaven is a film that recounts the exploits of Balián, a French blacksmith who moves to Jerusalem seeking clemency for his sins and those of his wife, who died by suicide. Once in Jerusalem he finds his way and what being a knight embodies. The film carries historical elements and is located in the moments before the Third Crusade, between the years 1185 and 1187.
The film begins with the arrival of Balián's father, Godofredo, baron of one of the possessions loyal to the King of Jerusalem. Godofredo asks his son to go with him to the holy land, but Balián decides not to accept his father's request, because he doesn't want any more problems and wants to live quietly there. But Balián, in a dispute with the town priest, kills him. In a scuffle to protect his son, Godofredo suffers a mortal wound. Before dying, he designated his son heir to his lands and distinguished him with the title of knight. Balián arrives in Jerusalem, and is considered by all to be Godofredo's son. He also realizes that the kingdom is divided into two parts, which fight against each other. On one side is the king, whose objective is to negotiate a long peace and harmony between Christians and Muslims. The opposing group headed by the Templar Order only thinks of continuing the fight against the Muslims.
The king of Jerusalem, Baldwin suffers from leprosy and will leave this life when he tries to stop Saladin, sultan of the Arabs, from conquering his territories. Before dying, the king orders him to kill one of the Templar masters, the king's brother-in-law, for his marriage to a sister of the monarch so that the Templar does not occupy the throne of Jerusalem. Balián maintains a loving bond with this married woman. After some strong doubts, Balián decides to ignore the king's wishes, and not kill the Templar, thinking about the salvation of his soul and attesting to his oath as a knight.
The newly crowned King of Jerusalem, a bigoted Templar, declares war on Saladin and leads his entire army across a barren desert to fight the Arabs. The lack of water will lead the Templar army to disaster, and Saladin's troops massacre the Christians.
Balian stayed in Jerusalem with the mission of defending the city. Besieged by Saladin, he courageously defends the city, while seeking an agreement with the sultan. His heroic way of defending the city, as well as his skill as a negotiator, signs a pact with Saladin. The terms of the agreement are summarized in not instigating the defenders in their withdrawal, not executing anyone, as well as protecting freedom of worship. Based on this agreement, Balián surrenders the city. Balián then returns with the king's sister from Jerusalem to France, where he will devote himself to working in his old profession, blacksmithing.