The Tears of Uther Pendragon (2) (S03E02)

Thanks to the Great Dragon, Merlin makes his way back to Camelot, only to discover that the kingdom is on the brink of invasion. Morgause and Cenred have formed an alliance, scheming against a vulnerable Uther. Initially hesitant, Cenred is persuaded by the knowledge that they have a traitor inside Camelot who will help them seize the castle. With Uther unable to lead, Arthur is forced to take charge and defend the fortress against Cenred's formidable forces. To complicate matters, Morgana unleashes a terrifying skeleton army, adding chaos to the siege. The survival of Camelot now hinges on Arthur and Merlin's combined efforts to fend off both the living and the undead. Will they prevail?