Ah yes, House of the Dragon! Unlikely as it is that a megabucks Game of Thrones prequel with a blue-chip cast could be forgettable, in its first two seasons HotD did not help itself, with the first either killing off its best characters too soon or recasting them to accommodate bewildering time jumps, and the second building and building to nothing. It returns for a third run without much wind in its dragon wings.

Breathe a fiery sigh of relief, then, at the news that this show has found its focus. The start of season three is a fine epic, balancing big battles with sharp two-hander scenes where dominance shifts and fatal personality flaws are forced out. Add the odd new face and a blast of comic relief here and there and you have proper Thrones.

Summarising House of the Dragon, especially as one of its weaknesses is or was overcomplexity, is impossible, but suffice it to say that a power vacuum has emerged in novelist George RR Martin’s fantasy realm Westeros, into which various rulers, royals and military commanders seek to step. Almost all of them are making a lethal mistake, with the first reckoning being the Battle of the Gullet, a naval smackdown that really should have been the season two finale.

An orgy of CGI carnage, the sea battle is impressive on that front but with smaller stories within to give the spectacle strong bones. Will the “Sea Snake” Corlys Velaryon (Steve Toussaint), a leader who thinks before he acts and is distracted by paternal guilt, be overwhelmed by the recklessly dashing Sharako Lohar (Abigail Thorn), who knows no fear or danger? After a crescendo of arrows, fire, deck sword fights, underwater punch-ups and dragonly intervention, we have an answer.

Incidentally, the jury is still out on whether the dragons make House of the Dragon better or worse. You can read them as a metaphor for weapons of mass destruction, wielded capriciously by leaders who can barely control them anyway, but it can be hard to reconcile their awesomeness with the humans effortfully chopping and hacking each other.

Anyway, Thorn’s wonderfully brash performance brings us one of three pivotal women whose refusal to heed advice will be their making or their downfall. Also gambling on the sea battle, albeit from afar, is thwarted queen Rhaenyra Targaryen (Emma D’Arcy), while Rhaenyra’s friend/foe/stepmother Alicent Hightower (Olivia Cooke) has to scheme to survive, her added complication being that she is the mother of Aemond Targaryen (Ewan Mitchell), he of the eye patch, the jawline like a blade and the eternal vengefulness of the bullied little brother.

D’Arcy and Cooke look ready to take over the show, with D’Arcy bringing the wounded ferocity of the forever overlooked, and Cooke artfully unreadable. The aftermath of the opening two episodes’ bloodshed is a rewardingly textured game, more sophisticated as drama than the show has been before, with some characters craving power and others lamenting that they weren’t more careful what they wished for.

Cutting imperiously through the middle is Matt Smith, devouring the role of unstoppable warrior and Rhaenyra’s uncle/husband, Daemon Targaryen. At least 100 characters fail to learn the lesson that running at Daemon with a sword ends with him lancing you through the Adam’s apple – but Smith is more impressive when swords are sheathed. Coming at Daemon with sharp words is foolish too. The smirk flickering around the edges of his mouth tells us to relax and enjoy the crimson chaos.

House of the Dragon is a less flippant show than Game of Thrones, and less reliant on sex and nudity to keep our attention: there is not that much hot D in HOTD. Instead it has moments of offbeat cuteness, like a dragon apparently abandoning its rider on a mountain top, only to reappear minutes later with two sheep, one of which it helpfully flame-grills; or the all-out comedy of Tom Bennett, once of PhoneShop, as the endlessly unlucky dragon rider Ulf.

Season three has one more weapon in reserve: James Norton has an early scene as new main player Lord Ormund Hightower. Is the joke where a snooty nobleman receives a letter from a messenger who reeks of faeces a new one? No. Does Norton make it funny? Yes, but then he vanishes again, kept in reserve by a show that has the confidence of knowing that its edge was never sharper.