With a definite shift to a darker tone, the destiny of Camelot now rests on the shoulders of a young man, as Merlin appears to have grown up. Shot on 35mm film for the first time, the show looks richer and benefits from some ambitious CGI work.

In story terms, two character deaths allow the series themes to develop; firstly, Morgause as her sacrifice frees Morgana from the role of henchwoman to become the lead villain, and secondly Uther, as his passing raises Arthur to the position of King with all the inherent responsibilities that brings.

New to the setup in Camelot is the shifty Agravaine (Nathaniel Parker), Arthur’s maternal Uncle who is Morgana’s inside man and takes every opportunity to undermine Arthur whilst posing as his most trusted advisor. In addition, the Knights are now present in force, though sadly Gwen appears to lose out in terms of screen time with little to do.

This first volume of Series 4 contains a strong batch of episodes with a good balance of comedy and drama. Blissfully devoid of trolls or goblins, you can feel some of the mythic Arthurian elements finally falling into place.

The two-part opener, The Darkest Hour, returns us to settled Camelot a year after the events of Series 3; Arthur rules in all but name while Gwen acts as nursemaid for the broken King, their relationship seems to be developing and Merlin appears happy with the Knights for friendship.

Then Morgana returns with stronger powers, tearing open the veil between the worlds of the living and the dead, allowing the wraith-like Dorocha to roam the land. She receives a fearful prophecy that Emrys will be her doom, but remains in the dark as to who he is. In order to heal the rift, the Knights travel to the Isle of the Blessed with Arthur intending to give his own life Lancelot, his eyes opened to Merlin’s importance, sacrifices himself to save Arthur and heal the tear.

In The Wicked Day, a bungled attempt on Arthur’s life transpires to be the catalyst for Uther’s death and the prince’s elevation to the throne. Phil Davis stars as the sinister showman who does the deed and Merlin’s gamble to show Arthur the value of magic goes disastrously wrong in a wonderful and game-changing episode, which is surely the most impressive on this set.

Guest starring James Callis (Battlestar Galactica), Aithusa is an enjoyable slice of boy’s own adventure with the hunt for a dragon’s egg that could have probably could have taken place at any point since Merlin was revealed as the last of the Dragon Lords.

His Father’s Son provides another strong guest turn, this time from Lindsay Duncan as the vengeful Queen Annis, providing a first challenge to Arthur’s Kingship. With Morgana stoking the fires on one side and Agravaine on the other, Merlin has to attempt to diffuse a situation that goes to the brink of all out war.

Finally, in A Servant of Two Masters, Morgana strikes directly at Arthur by attempting to use Merlin to kill him prompting a confrontation between the two.

Extras: Audio commentaries from the cast and crew on the first three episodes feature director Alice Troughton as well as Katie McGrath, Angel Coulby, Rupert Young and Colin Morgan. These are entertaining, if a little incoherent at times, especially on Episode 2.

A clutch of deleted scenes are provided in which interchanges between Merlin and Arthur are most interesting, offering some further male bonding. In addition, there is a great moment with Lancelot where Merlin talks about his struggles with hidden magic and his desire for Arthur to know his secret.

Outtakes provide general silliness and corpsing, while also included is a quite lengthy sequence of storyboards, which while interesting, is strangely presented without commentary or live action for comparison.

Released on DVD on Monday 28th November 2011 by Fremantle Home Entertainment.

> Buy the Series 4 Volume 1 DVD on Amazon.

Watch the Series 4 trailer …