While Camelot prepares to celebrate peace with Mercia's visiting ruler King Bayard, a priestess named Nimueh forges a poisoned chalice and replaces it with one due to be given to Arthur. She then disguises herself and plants suspicion in Merlin's mind about Bayard's true intentions. After Merlin accuses Bayard of trying to poison the Prince, Uther forces Merlin to prove his word by drinking from the goblet, not caring if he dies. Despite Arthur's protest, Merlin drinks from the goblet and is poisoned, collapsing. Bayard is framed and imprisoned, whilst Gaius deduces the only antidote is from an incredibly rare flower, which only grows in certain caves. Uther sternly forbids Arthur from undergoing the perilous journey, especially for a 'disposable' servant like Merlin. Despite his father, Arthur bravely rides out to find the flower and, even though Nimueh deliberately leads him into the paths of deadly monsters, he succeeds and brings the flower back to Camelot. Upon his arrival, a furious Uther locks his son in the dungeons as punishment for his disobedience and cruelly crushes the flower but, with the help of maidservant Gwen, Merlin receives the antidote and is cured.
