This was shown on TV when I wanted to see Pillars of The Earth. The story of La Commanderie is not as complicated as the Pillars of The Earth (I am referring to the book as I haven't seen the movie), but is quite good. Set in 1375, when France suffers because of a long war and black death, the Hospitaller Order of Saint John of Jerusalem and Rhodes builds a citadel known as la Commanderie d'Assier. This place offers help and support for those in need.
The purpose is noble, but not in practice. The main character, Captain Thomas Cortemain, the commander-in-chief of the citadel, is not what you think a hero should be. He tries to make some extra money for himself by threatening the farmers. He makes an agreement with a band of mercenaries who rob travelers. He cheats on the girl who loves him. The Order soon finds out about what Thomas did to the farmers, but lets him go if he helps searching for the lost treasure of the Templar. Thomas doesn't know that the guardian of the secret is no other than his childhood sweetheart, Constance, who has married the country squire: Geoffroy de Montet. Meeting her again makes Thomas believe that they are destined to each other.
I think except Commander Roger de Neuville, other characters in this are corrupted. The beautiful Constance guards a secret so big that she will not hesitate to murder. Her maid is even meaner. Everyone has secrets. The farmers live poorly because the church takes too much. The inquisitors are feared by everybody.
Thomas stops searching for the treasure because of Constance's doing. She poisons herself and accuses Thomas, who begs one of the saints to save her, and promises he will not continue his work. However, the Pope gives Thomas a letter to free him from his promise. In the end, with the help of Master Sabet, the doctor in the citadel, Thomas finds "the treasure" - some IOU letters of how the church owed the Knight Templars. The Duke of Anjou refuses to believe this and accuses Contance has taken the treasure. He orders Thomas to torture her, which leads them to a false treasure: a document of how the crusades to Jerusalem was not recommended. As the Duke of Anjou wants the treasure to finance the next crusade, he must cancel his plan.