Below, get a sneak peek at tomorrow's episode of the Syfy hit MERLIN. In the episode titled 'A Lesson in Vengeance,' King Arthur is the target of a dangerous assassin - his wife and Queen, Gwynevere.

The story is based on Sadie Jones’ bestselling novel and centers on Lewis Aldridge, a boy who loses his mother at a young age and never really recovers from it. The show follows him as he returns home ...