Merlin approaches the finish line with a powerful story that sets-up the big two-part finale.

It begins with Arthur, Merlin and the Knights discovering a Saxon camp littered with dead bodies. Mordred spots a hooded figure fleeing from the site and after giving chase, realises it is Kara, a druid girl from his past. He naturally tells her to flee, but unfortunately for him Merlin has spotted the pair and is only suspicious of his actions. When Kara is later caught and imprisoned Mordred, Merlin and Arthur’s loyalties are all tested to breaking point.

This is another dark episode. With such weighty moral issues at the heart of the story, it’s no surprise that this episode contains very little humour. It would feel out of place this late on anyway.

Last week’s episode was very Merlin-centric, and, unsurprisingly, this time it’s Mordred’s turn to take the limelight. Some fans will begrudge the attention being pulled away from Merlin again, however it’s definitely required to give him a believable motive to turn on Arthur. Throughout Series 5, Merlin has repeatedly been told that Mordred will cause the Arthur’s downfall and cannot be trusted (not to mention that vision). This episode sets the wheels in motion as Mordred begins to walk the dark path. However, the events that lead him there are more than a simple case of him just “turning evil” because he is required to. In fact, he has good cause and this episode really makes the viewer question who they should be siding with.

Alexander Vlahos has been a great addition to the show, although, like most of the Knights, terribly underused since his introduction in the opener. Thankfully, he gets his best material of the series here as he is emotionally torn between his own kind and Arthur. There’s a fantastic build-up of quiet, contained rage that eventually culminates in an explosive outburst. Guest star Alexandra Dowling is good as Kara and she has a believable chemistry with Vahos despite only being introduced here.

Usually Merlin is the character we root for without question, however some of his actions here are questionable and he comes across as a little harsh at times. Even Gaius points out his hypocrisy. It’s a bit of a role reversal and this does give Colin Morgan something new to play with. He is reliable as ever with his performance, even though his screentime is fairly short this week. He communicates a lot here by mere looks alone. As for Arthur, he is not vilified for the sake of the story and his actions are more or less justified. He too debates how to resolve an increasingly difficult scenario and looks for a solution that seems impossible to find.

Overall, a great instalment that forces the audience to question where their sympathies lie. By the time the final scene rolls around you’ll be even more desperate to see the finale and, judging by the preview, it will not be one to miss!

9/10

The episode airs Saturday 15 December 2012 at 8.15pm on BBC1.