The witch Morgana (Eva Green) murdered her father Uther (Sebastian Koch), who was the king, in an attempt to usurp the throne to satisfy her ambition to ascend the throne. At this juncture, the wizard Merlin (Joseph Fiennes) went out to find King Uther's illegitimate son Arthur (Jamie Campbell Bower), and brought Arthur back to the palace before Morgana ascended the throne. Arthur pulled out the sword left in the stone by the Roman army, proving his identity and gaining the recognition of his subjects. At the same time, he also reunited with his first love Gwenevere (Tamsin Egerton), and did not change his old feelings for her. Who knew that at this time Gwenevere was about to marry a man named Leontes (Philip Winchester). At the same time, Morgana, whose conspiracy had not yet succeeded, would naturally not give up and pointed the spearhead at Arthur.