There's something in the forest in 16th century Scotland. It's been there for years. Anyone who sees it doesn't live to tell about it, and it moves seamlessly between land and sea, leaving nothing but body parts in its wake. With a body count in the thousands, it's a legendary historical horror story that's supposedly true.
The creature is a goblin spider. It's a goblin who's also a spider...or, is it? We'll see that things aren't always what they seem on an extended creature of the week.