Three years have passed since the wedding of Arthur and Gwen, the Round Table has been formed and (although the details are vague) Morgana has been imprisoned for a couple of years, but now Sir Gwaine (Eoin Macken) and Sir Percival (Tom Hopper), along with their retinues of knights, have disappeared on an expedition to the snowy north.
Arthur, determined to track down his missing men, has heard rumours that Morgana has taken over an ancient fortress and is hunting through the tunnels and mines below it for a mysterious artifact.
Instead of a direct approach, at Gwen's suggestion, the king leads his troops (along with Merlin, of course) through the lands of his ally Queen Annis (Lindsay Duncan), so he can attack Morgana unexpectedly from the west.
However, there's a traitor in Camelot and Morgana gets tipped off and ambushes Arthur's troops before they can reach her fortress. Arthur and Merlin becomes separated from the battle and end up wandering the wilderness, while Camelot's battered forces retreat to their homeland.
Season Five of Merlin hits the ground running and although there are moments of levity (such as Merlin juggling for the court of Queen Annis) there is a distinctly darker tone to the episode than we've generally felt in previous years. It is almost as though the show has matured into an edgier format - and I like it!
There's magic aplenty, from low-key legerdemain and a bit of "sticks-to-snakes" right up to full-on prophetic visions of Arthur's final battle and his death at the hands of Mordred. Even the great dragon gets to put in an appearance with some words of wisdom for Merlin.
Which isn't to say that certain other elements of its earlier years haven't been forgotten - there's plenty of man-candy for the female viewers (and certain sections of its male audience as well), especially as Morgana's prisoners are apparently compelled to work the mines shirtless!
Morgana, of course, oozes sex appeal and menace in equal parts, but she isn't left to carry the torch for the dark side alone and is given able support from the always excellent Liam Cunningham as warrior-wizard Ruadan and Alexander Vlahos as the grown-up Mordred.
Gwen also quickly proves herself as a badass queen - when she unearths the traitor at court - which was a pleasant surprise. Let's hope she continues in this vein... and maybe even butts heads with Arthur on occasion.