“Merlin” fans need to take note of “Arthur’s Bane, Part 2,” which airs tonight on SyFy at 10/9c. For all his life, Merlin knew that he would help Camelot and Arthur, but that might be in doubt now.

Here’s the official rundown:

As ‘Arthur’s Bane, Part 2’ begins on Friday, Jan. 11, at 10 p.m. ET/PT Friday on Syfy, both Merlin and his king have been captured by henchmen working for Morgana – single-minded in her determination to find the mysterious ‘Diamair.’ Among their captors is Mordred – the Druid first encountered as a boy, now a man whose destiny Merlin knows: Arthur will die at Mordred’s hand.

Is Mordred, in fact, Arthur’s bane? Or could the prophecy be wrong? Could there be another danger threatening Arthur?

As the episode progresses, Mordred’s allegiances are called into question, and his magical (and secret) nature stands in strong parallel to Merlin’s own life. This comparison between Merlin’s magical nature and Mordred’s resonate throughout the episode – and this final season of ‘Merlin.’

Bradley James–who plays Arthur–talked about the significance of magic in “Merlin.” “Because of the significance of what having magic means, the gravitas of that, it makes sense Merlin has never said anything to Arthur,” said James. “I don’t think it’s ever been about Merlin lying to Arthur – I think it’s been about the safety of Merlin, not to mention the safety of the kingdom.”

Colin Morgan–who plays Merlin himself–also talked about Alexander Vlahos, who is thrilling as Mordred.

“Alexander Vlahos is just extraordinary,” said Morgan. “He’s come into the series very late in the game, but brought with him a completely realized character. Alex really understands who Mordred is – and its exciting to see what he does with the character all throughout this final season.”