After winning a war to become king of England, Uther Pendragon (Pierce Brosnan), is disguised using magic by Merlin (James Cosmo), he then has a child with Igraine (Helena Bonham Carter), the wife of his defeated enemy. After the child his born he is left in a forrest where Merlin finds him and brings him to Ector (Liam Cunningham). At 18, Arthur learns of his royal linage and he is led to a sword in a stone no one could remove. When Arthur pulls the sword he becomes the king of England. As the king, Arthur is advised by Merlin who helps him form a council of knights. With his wife and his knights Arthur must battle his half-sister, Morgan le Fay (Eva Green), who wants to take over England.
