Series 4 Episode 8 airs at 8.15pm on Saturday 19th November on BBC One and sees a mysterious illness draw Merlin to a distant village. But it soon becomes clear that there is more at stake than just his well-being as something sinister turns the air sour.

> Order the Series 4 Volume 1 DVD on Amazon.

In this clip, Merlin is disturbed by a dark shadow as it flickers past the window late one evening…

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