Daenerys Targaryen has been a problematic character for long stretches of Game of Thrones. While her introduction and interactions with Khal Drogo in season one provided some of the better material in the show’s early days, her story and character faltered heavily in Season 2’s lengthy stop-off in Qarth. But here, she provides arguably the most rousing moment of the series to date, as she gets to have her cake and eat it too in liberating the Unsullied, and convincing them to remain and fight for her anyway, of their own free-will.

It’s a scene on a scale with Season 2’s Battle of the Blackwater (albeit shorter) and allows Dany’s dragons to let-rip in earnest for the first time. If the CGI shots of her army on the march aren’t entirely convincing (the dragons are flawless), they are at least very reminiscent of the aesthetic used in Starz’ Spartacus series, and that’s no bad thing (the weighted shot of Dany discarding the whip could also have come straight from that show).

The sense of scale is admirably conveyed, while Dany proves herself to be a savvier commander than anyone – even her closest companions – could have suspected. Emilia Clarke gets her biggest moment of the series, and even though it’s delivered in another language (and isn’t it great that she understood the condescending slaver all along?), Clarke sells it completely.

There are several other stand-out sequences in the episode. Varys has been conspicuously absent for the early part of this season, but Conleth Hill has the lion’s share of this episode to bring us more of his soft-spoken wisdom and politely scathing wit.

His recounting of how he became a eunuch is chilling, and while we’ve been tracking Daenerys’ quest to claim her throne midway along its progress, here we see the end of Varys’ quest for vengeance, in horrifyingly cold fashion. Varys is unquestionably one of the better players at this game, and in staying alive to spite the world he’s risen to be one of the most powerful figures in it.

If Varys has achieved his goals, one character whose story may only just be beginning is Jaime Lannister, who’s a broken man having lost his sword-hand. He’s close to giving up, until Brienne gives him a talking-to. Like Varys, he’s been maimed and treated inhumanly (the severed hand dangling around his neck? Sick.) but ultimately elects to stay alive rather than give up and let the world defeat him. But with only one hand, will he be able to drag himself back up to a similarly powerful position?

In the North, the tensions among the brothers of the Night’s Watch finally come to head at Craster’s, where Burn Gorman has turned up as a thus unnamed brother to ignite the mutiny that ultimately ends up extinguishing Commander Mormont, Craster, and countless others.

We’ve seen more of the Night’s Watch partaking in dull, manual labour than we have in battles with the undead, so we have more connection to the idea of them being over-worked, cold and hungry mutineers than we do the idea that they’re fleeing an army of White Walkers, and the explosion of violence at Craster’s keep feels merited; it’s ill-advised but fully understandable.

Theon, meanwhile, finds Iwan Rheon’s rescuer to be just another form of torture, as he secretly escorts Theon right back to the dungeon he’s just liberated him from. If everyone else is moving at differing stages of their journey, Theon Greyjoy is going in circles. It’s as confusing for the audience as it is for poor Theon, whose current situation along with the self-realisation that he’s always made bad choices, confirms him as perhaps the sorriest character in a world that is full of them.

Game of Thrones can’t possibly provide episodes like Blackwater every week, nor even moments like Dany’s triumphant power-play at this episode’s climax, but when it does break out the big moments, it knocks them out of the park. It’s tempting – and not just for the allusion to the show’s title – to call that moment (and this episode) a game-changer, but we’ll have to wait and see what ramifications follow.

Daenerys Targaryen has proved herself to be intelligent, fierce and compassionate; she has three dragons, an unfaltering army, and she’s on the march. Watch out, Westeros.

Aired at 9pm on Monday 22 April 2013 on Sky Atlantic.

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