Andrew Scott in His Dark Materials series 2, BBC One (Photo: BBC)

Now that’s more like it. Whereas last week’s episode of His Dark Materials felt lethargic, resorting to lots of world-building and not a lot happening, episode four accelerates the story. It proceeds like a mixture of the greatest fantasies that have fired up screens big and small, all while growing out of its own organic material.

Although the series’ sporadic fairytale narration has no regular consistency, coming and going as it pleases, its opening presence here provides a thick and mythical flavour. Writers Jack Thorne and Namsi Khan are transparently influenced by Lady Galadriel’s prologue for the first Lord of the Rings film. But instead of the One Ring, it’s the subtle knife: Æsahættr.

They give you its backstory, why it was crafted – gestating into the reasons why the very Italian Cittàgazze is empty of adults and filled with Spectres. And now, finally, you get to witness its power.

Giacomo Paradisi (Terence Stamp) teaches Will (Amir Wilson) about the subtle knife with Lyra (Dafne Keen). Photo: BBC

Will and Lyra re-enter Cittàgazze after Lord Boreal tasked them with finding the knife. They venture into the Torre degli Angeli, i.e. the Tower of the Angels. There’s a frightening mystery to it, the entrance deliberately obscured. (To make another geeky connection, it’s a lot like the Qarthian Houses of the Undying in Game of Thrones.)

Once they find their way inside, they come across Giacomo Paradisi (played by veteran fantasy actor Terence Stamp) bound and gagged towards the top. Without giving too much away, a furious fight breaks out, putting Will’s boxing skills to good use. In the book these scenes are more graphic. Director Leanne Welham (The Trial of Christine Keeler) retains the blood but in a precisely family-friendly fashion: briefly and out of focus, seeing dripping red blurs before cutting away. A perfect compromise.

Then we enter a brief mentor-student relationship between Giacomo and Will, the former training the latter in the ways of the subtle knife. This is very much Will’s episode, unlocking his full potential, but Lyra’s still a vital influence – more so than in the book. Often she is, bizarrely, the more rational-minded one of the two. She breaks Will out of his impassioned stares, pulling him away to get a bloody move on. Also, they’re becoming closer: her daemon Pan stepping nearer than is socially acceptable.

Lee Scoresby (Lin-Manuel Miranda) chatting with Jopari (Andrew Scott), his osprey daemon up above (Phoebe Waller-Bridge). Photo: BBC

Running concurrently with Will’s storyline, in a brilliantly appropriate parallel structure, is the meeting between Lee Scoresby (Lin-Manuel Miranda) and Stanislaus Grumman, otherwise known as Jopari, or John Parry, Will’s adventurer father. And lo and behold, hot priest Andrew Scott himself finally emerges out of old photos and BBC News footage to play the role in his full physical form. Jopari is a shaman and has a spiritual aura about him, one you can’t entirely trust.

But guess who introduces him, as Lee and Hester canoe through a swamp? Jopari’s osprey daemon, voiced by Phoebe Waller-Bridge. Yes, there are plenty of reasons to love episode four.

It’s one of the most satisfying episodes of His Dark Materials so far, diving into the ecstatic riches that fantasy can provide. The action scenes are fast and violent, with choreography to vibrate through your soul where your inner daemon lies. After the speed bump last week, the series has now recovered and drives into something spectacular.

His Dark Materials series 2 continues on Sundays at 8:10pm