The young warlock struggles to recover from the serket's poison, as the fantasy drama continues. Meanwhile, Morgana and Morgause are free to step up their plans for the invasion of Camelot.
Morgause continues her manipulation of Cenred, as he prepares to launch an attack on the citadel, but Cenred knows he cannot take the castle alone. Morgause promises him that they have an ally within King Uther's court who will ensure they win the day - no one can fight a battle on two fronts. Morgause gives Morgana a powerfully enchanted rowan staff to aid her in her magical treachery.
King Uther is still unable to rule as he recovers from the enchantment inflicted by the mandrake root. So, as Cenred's army attacks the citadel, Camelot's fate now rests on Arthur's shoulders. The young prince and his men fight bravely but, just as they think the tide might turn, Morgana plays her deadly card. In the vaults beneath Camelot she uses the rowan staff to summon a skeleton army to wreak havoc within the castle walls.
Arthur and his men cannot hold off both an army of the living and an army of the dead. Merlin knows that their only hope is for him to stop Morgana and vanquish the enemy within. Will he be able to do so without revealing his own magical powers?