Arthur's Bane (2) (S05E02)

As the first light of day pierces the frozen tundra, Merlin and Arthur push themselves forward, fatigue weighing heavily upon them. Each agonizing step brings them closer to the ominous fortress of Ismere, heightening Merlin's anxiety. What scheme is Mordred concocting? Meanwhile, Morgana and the druid Ruadan (Liam Cunningham) delve into the fortress's dark catacombs, searching for potent secrets. This time, it seems that Merlin can’t prevent Arthur from stepping into danger. In this desolate and fleeting landscape, one truth stands clear: the monumental challenge for Albion has begun.