Coming off its strongest episode to date, Atlantis had a lot to live up to and while 'The Grey Sisters' is perhaps not as visceral or immediately thrilling as its predecessor, it arguably has more substance.
Writer Howard Overman and director Declan O'Dwyer's third collaboration for the show affords certain characters - and this series' arc - significant development, certainly doing more for the villain Pasiphae than almost the previous 18 episodes combined.
While it's rather light on peril, this more thoughtful Atlantis allows the audience - and the show's writers - to take stock of the series as a whole so far, before we push on with the next chapter in 2015.
When we left our heroes, Ariadne (Aiysha Hart) had been mortally wounded by the turncoat Medea (Amy Manson) and we pick up with a vengeful Jason (Jack Donnelly) doing his best Liam Neeson bit - "I will find you… and I will kill you" - as he pursues the witch.
Medea slips away, while the Queen is barely clinging onto life, her wound refusing to heal - a predicament which allows Juliet Stevenson's Oracle to briefly step out of the shadows and prove she's adept at more than spouting mystical prophecies.
Medea's dagger, the Oracle reveals, was enchanted with dark magic. Only the Grey Sisters - archaic goddesses from Greek mythology - hold the secret to saving the Queen's life, but while they serve a plot purpose in educating Jason on his connection to Medea, these titular harpies are in fact rather incidental.
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His efforts to save his beloved briefly land Jason in Pasiphae's custody and it's this confrontation between mother and (unwitting) son that is really at the heart of the episode. It's a little frustrating that Pasiphae's survival and escape from the cave system go unexplained, but otherwise 'The Grey Sisters' affords Sarah Parish some of her best ever material on the series.
Both she and Donnelly are excellent throughout their confrontation, as Pasiphae is revealed to be not quite the Black Hat you've always assumed her to be - her reasonings behind what she does and why she feels she would be a better monarch than her former step-daughter are not entirely unconvincing.
There's a genuine desire on her part to reconnect with her son, and she displays genuine upset when he persists in attacking her. Jason's refusal to compromise or change his views, likewise, casts our heroic lead in a rather unflattering light.
Atlantis is always going to be a big, broad family series, but it's good to see Overman and others exploring those moral shades of grey as much as the fantasy adventure format will allow.
Ariadne is, of course, ultimately restored by Jason's efforts and the first thing she does once recovered is propose to her saviour - for once though, I suspect it's not Ariadne's skittishness that will prove an obstacle to their happiness, but Jason's connection to Medea.
It's pretty clear where that relationship is going - Medea may have been "touched by the gods" but now she wants to be touched by Jason too - but am I alone in picking up on the ick factor inherent in this coupling? Aren't these two related - and isn't Medea now fully aware of that fact?
Aside from a few concerns it elicits about the show's future though, 'The Grey Sisters' is a fulfilling experience - action-lite, but fleshing out a few of the show's major characters in a surprising and satisfactory manner.
In fact, bar the rather weak 'Telemon', Atlantis has been really rather impressive in 2014. It's evident that the minds behind the show have learnt from the first series, amping up what works - the action, the fantastic visuals, the relationships between characters - and dialling down what didn't - the unconvincing CGI beasties and awkward slapstick.
Though that first series as a whole left me rather nonplussed, I'm now looking forward to the seven episodes coming up next year with much anticipation.
