I have long felt that Merlin makes for great Dungeons and Dragons-y inspiration, but it has never been so 'on the nose' as in The Dark Tower.
Morgana kidnaps Gwen and holds her hostage in the dread Dark Tower and Arthur, Merlin and their usual coterie of close knights ride to the rescue.
Even getting to The Dark Tower is a struggle for our heroes as it lays beyond the Impenetrable Forest - where Merlin has an encounter with the fairy queen Mab (Kelly Wenham) who warns him that one of their party will not return to Camelot.
Unfortunately the build-up to the knights' arrival at The Dark Tower takes so long - as brilliant and engaging as it is - that their time actually within in the spire seems rather rushed and they only face a couple of obstacles (the pressure pad trap from Raiders Of The Lost Ark and a 'dancing sword') before reaching Gwen.
While all this has been going on, the young queen has been tormented by the constant drip-drip-drip of black ooze from mandrake roots, ghostly screams and cruel illusions as Morgana tries to break her spirit and drive Gwen as insane as she has clearly become.
After the hurried conclusion of the main plot though we get the denouement which shows the sub-plot of Morgana's mental torture of Gwen is far from over.
I can't help but wonder if this is perhaps Merlin's replacement for the traditional love triangle which spells the end of Camelot in Arthurian mythology, and instead of Gwen betraying Arthur with Lancelot she sells him out to Morgana, instead?
As the show has progressed over the years, sorcery has become more and more prominent and The Dark Tower epitomises this as pretty much everything that anyone interacts with throughout the story is magical to some degree, from Morgana's initial ambush, through the mystical forest to the mental torments of the tower itself.
Hopefully, this is laying the groundwork for Merlin to finally be able to "come out of the magical closet" and offer his sorceress skills to Arthur publicly.