Watch a sneak peek for tomorrow night’s episode of Merlin, the big Mordred episode “The Drawing of the Dark.”

Right now, the sneak peek is only available to watch on BBC’s website.

This clip depicts a very intense scene from the episode, which is probably going to be a key moment for sending Mordred to the dark side.

Mordred returns to the castle to be confronted by Merlin, and tells him that he’s been helping an old Druid friend. He asks Merlin not to tell Arthur, as of course the girl will be killed for having magic – and Merlin promises Mordred that his secret is safe with him.

But will it be?! Judging from the promo, it looks like Mordred’s friend Kara will indeed find herself in trouble with the laws of Camelot. Did Merlin break his promise to Mordred, or did Arthur find out in some other way? And will Merlin help the girl escape?

Somehow we doubt it. With only two more episodes left after this one (the two-part finale, airing December 22 and December 24), surely this must be the turning point for the young Druid who is destined to kill Arthur at the Battle of Camlann?

How will it all end?! We’ve shared our best theories, but we want your ideas too!