His Dark Materials episode 6 review: The first cut is the deepest

From the episode’s start the slow, cold dread and clinical corridors of Bolvangar build up to an almost unbearable level of tension, with Lyra trying her best to rally the other children before they, one-by-one, have their daemons cut away by the scientists there (Amit Shah’s unhappy technician and up-and-comer Morfydd Clark’s slightly deranged nurse being particular highlights).

Despite her best efforts, soon it’s Lyra under the (slightly subtle) knife, which itself leads to the literal mother of all showdowns when Mrs Coulter (Ruth Wilson) discovers it’s her own daughter about to be severed. The following téte-a-téte between Keen and Wilson is, despite all the bangs and whistles at the end of the episode, the definitive clash this week, and one of my favourite moments in this adaptation.

From the start of this series Keen has done solid work as Lyra, but here she really comes into her own. Her cold rage at Mrs Coulter (which reminds of Keen’s acclaimed role in superhero movie Logan) makes her a charismatic anchor in the scene as her mother’s cool finally slips away. Somehow, they’ve traded places – the emotional, wayward child and the ice-cold schemer – as Mrs Coulter tears up and shares her innermost feelings (Wilson continues to give the character a more sympathetic mien than she had in the books) while Lyra coolly lies and tricks her into allowing an escape.

There’s something intensely satisfying about Keen’s definitive takedown of all the lies she’s being fed about how brilliant, how clever this severing process is with one bitter line, taken directly from Pullman's text: "If it was so good, you should have let them do it. You should have been glad."

A moment later, the pair are mirrored in their howling animalistic rage, and it’s hard to imagine another pair of actors pulling this relationship off with such aplomb.

Elsewhere, there were showier battles as the Gyptians fought their way into Bolvangar, Iorek chomped down on some baddies and witch Serafina Pekkala (Ruta Gedmintas) showed off just what her people can do for the first time.

Later, a horror movie-esque scene in Lee Scoresby’s (Lin-Manuel Miranda) balloon almost overloaded us with exciting visuals for the episode as the gang are attacked by cliff-ghasts and Lyra is cast off into the frozen unknown.

But for me it was the quieter moments, like Lyra and Mrs Coulter finally facing off, or the horrible, dead-eyed children whose daemons were taken away (unlike last week, the horror of this mutilation hits home much better) shuffling along that really made my heart race faster.

Genuinely, everything came together this episode – the VFX, the set design, the props, the costumes, the actors, the slow-build machinations of the script over the episodes before – to deliver a terrific piece of TV that more or less justifies this adaptation all on its own (even if they do keep making big changes to the source material).

Whether they can keep the momentum up remains to be seen. But as Lyra confronts the King of the bears and earns herself a new name next week, I have high hopes…

His Dark Materials returns to BBC One at the later time of 9pm on Sunday 15th December