See Merlin star Colin Morgan reflect on last night’s episode “A Lesson in Vengeance,” and the promo for next week’s “The Hollow Queen.”

The show took a turn last night when the latest enemy of Camelot is revealed to be none other than Guinevere, who seems to be in an alliance with Morgana to kill Arthur. It almost works, too, but luckily Merlin manages to save Arthur with his magic at the last minute – but Gwen is still at large, and as we saw this week, it’s her word against Merlin’s.

See what Colin Morgan has to say about the twist:

In the video (which seems to have gone a little wonky during uploading), Morgan explains that this episode is the first of three that will explore Gwen’s turn to the dark side, and that Merlin is still trying to work out exactly what is causing her to act this way. He also praises his co-star Angel Coulby, who he says, “Is fantastic, the scenes I had with her were brilliant because it was her, but there was something else going on.”

As for his own character, Merlin, “very much becomes like an investigator in this episode,” Morgan says. “He’s a little bit Sherlock Holmes-y in terms of how he’s going about it.” And, Morgan says, “it’s a difficult situation; how do you broach something that is so truly unbelievable? Especially when the Queen has a lot more power over you? And she can do essentially whatever she wants.”

But while it might be a frustrating situation for Merlin, Morgan thinks the episode will be a, “brilliant one for viewers to see, it’s Gwen like we’ve never seen her before, and Angel how we’ve never seen her before. And it also sets about the impossible task that is yet to come.”

You can also watch the promo for next Friday’s episode “The Hollow Queen,” where Gwen sets her new plan in motion:

How do you think this will all be resolved? Is Guinevere lost for good, or will Merlin and Arthur find a way to bring her back?

Merlin 5×08 “The Hollow Queen” airs next Friday at 10/9c on SyFy.