When a mysterious warrior challenges Arthur to a duel, no one could possibly predict the devastating chain of events that is set in motion - least of all the young prince himself.

Arthur and Merlin soon find themselves on a strange quest at the behest of the beautiful Morgause. Through her, Arthur discovers a dark secret which threatens to bring about the downfall of the kingdom.

Dignitaries from rival kingdoms descend on Camelot for peace talks, but what King Alined really wants is war and he'll do everything in his power to stir up hostilities, even if it means using magic.

Alined's jester Trickler puts a spell on Arthur to make him fall madly in love with rival King Olaf's daughter Vivian. Chaos reigns in the palace and Camelot is once more poised on the brink of war.

Can Merlin free Arthur's heart before the prince loses his head in battle?