Uther holds a feast for his guests and while Trickler amazes everybody with his magic, he also manages to cleverly steals a strand of Vivian's hair. With this he makes a love potion, which he then proceeds to drop into Arthur's eyes as he sleeps.
Merlin and Gwen, despite seeing a change in Arthur, initially assume that the Prince is showing affection towards Gwen. However, Merlin quickly realises that Arthur is lusting after Vivian and so he tells Gaius of the Prince's sudden change in character. Gaius realises that if Arthur is caught with Vivien alone in her chamber then there night be war. Merlin does his best to keep the Prince away from Vivian.
After seeing the lock of Vivian's hair, Merlin realises Arthur is enchanted and decides that King Alined and Trickler must be the culprits behind the plot. Meanwhile, Trickler has realised that Arthur may love Vivian but the Princess does not return the feelings. The Jester cuts a lock of Arthur's hair and uses the same enchantment on Vivian.
Its not long before King Olaf has been made aware of Arthur's intentions towards his daughter and arrives at Arthur's chamber. Merlin has also come to the chamber and casts a sleeping spell on Vivian and hides her in Arthur's closet before anyone realises she is there. King Olaf finally accepts his daughter is not in the room and leaves.
After coming up with a counter spell Merlin finds Arthur and Vivian kissing passionately in the Princesses chamber but can't break the enchantment. Then King Olaf, Alined and Uther arrive and enraged Olaf challenges Arthur to fight to the death. Arthur agrees as he loves Vivian.
While under the influence of the love spell Arthur looks like struggling with his duel with Olaf and everyone realises that whoever wins the challenge there will be war between the two kingdoms. Can Arthur survive the fight and will Merlin find the magic to rid the prince of the enchantment?
