Rhys Rusbatch

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. But Arthur and Merlin soon find themselves on a strange quest at the behest of the beautiful Morgause (Emilia Fox). Through her Arthur discovers a dark secret which could bring about the downfall of the kingdom.

The first episode of this exciting two parter sees Uther captivated by his latest guest, the beautiful Lady Catrina (Sarah Parish). Arthur is appalled by his father’s flirting but Merlin’s wary for a different reason – he suspects she is really a troll! Catrina and her strange servant Jonas (Adam Godley) are welcomed into the heart of Camelot and it is up to Merlin to prove she’s a monster and save Uther from ruin. Unfortunately, Catrina has her sights set on a far greater prize than the King’s heart. Can Merlin overcome her powerful troll magic before it’s too late?

Newly crowned Queen Catrina (Sarah Parish) settles in as Camelot's first lady. As her true troll nature surfaces her influence over Uther increases and the repercussions are felt throughout the kingdom. When Catrina accuses Merlin of stealing, he is driven into hiding. Forced to sneak around the castle, Merlin must find a way to expose Catrina's true form without getting caught – and beheaded. But even if he succeeds, will this be enough to break her powerful magic?