Synopsis

As the first light touches the frozen tundra, Merlin and Arthur are nearing the point of collapse. With each agonizing stride, the fortress of Ismere grows closer, and Merlin’s apprehension deepens. What design is Mordred weaving? And what potent secrets are Morgana and the druid Ruadan (Liam Cunningham) seeking within its labyrinthine catacombs? It seems this time, even Merlin cannot prevent Arthur from stepping into a trap… For in this desolate and shifting landscape, one truth remains: the gr