Part One: An ugly old troll drinks a potion transforming herself into the glamorous Lady Catrina, who arrives at Camelot with her servant Jonas. Gaius, who has met the real Catrina, and Merlin, who witnesses her true identity, are unable to convince bone-headed Uther of Catrina's real nature, especially when she bewitches him by giving him a magic pendant. Merlin attempts magic to expose her but she is too strong and it is too late to stop her marrying the king and becoming the queen of Camelot.
—don @ minifie-1