In season 3, a year after being taken away from Camelot, Morgana is found bruised in the woods and claims to have been kidnapped by bandits, and events quickly begin to unfold.
In season 4, unseen ghosts begin to attack the kingdom. In Camelot, where a weakened Uther has given much of his rule to his deceitful brother Agravaine, Merlin senses what is happening but finds his magic insufficient to stop it.