Season synopsis
Contains spoilers for this season and earlier seasons.
After a year missing, Morgana returns to Camelot, but Merlin discovers she has joined Morgause and is working against Uther from inside the court. Their first attempt to weaken the king draws Cenred’s forces and an enchanted dead army against Camelot; Arthur must lead the defence while Merlin breaks the spell’s source. Morgana takes credit for saving the kingdom, keeping her betrayal hidden. Later, Merlin’s mistake in the Crystal Cave leaves Morgana gravely injured; as Uther grieves, he admits to Gaius that she is his daughter. Morgana remembers the confession after Merlin heals her and turns fully against the family that concealed her parentage.
Morgana and Morgause continue to target Arthur, Gwen and Uther, while Arthur’s choices point toward a different kind of rule. In the finale, the sisters take the Cup of Life and use it to make Cenred’s army immortal. Cenred is killed, Camelot falls, and Morgana reveals both her allegiance and her claim as Uther’s daughter before being crowned queen. Arthur gathers his allies outside the city and knights Lancelot, Gwaine, Elyan and Percival, setting aside Uther’s restrictions on knighthood.
Merlin and Lancelot reach the Cup while Arthur and the others free Uther and the imprisoned knights. With Gaius’s help, they empty the Cup of blood, ending the soldiers’ immortality; the army is defeated and Camelot is retaken. Merlin and Gaius overpower Morgause, but a search of the rubble finds neither her nor Morgana. Uther remains king, while Arthur’s new knights and the Round Table signal a change in the kingdom’s order. At the end, Merlin embeds Excalibur in a rock.