This week’s Wizards Vs Aliens story, ‘The Key of Bones’, is Season 3’s penultimate adventure and very much feels like it.

It seems like most of this story exists to set up what’s to come in next week’s two-part finale; indeed, the real action of this story doesn’t come until Part 2. It’s a complex, multi-layered set-up structure.

But Part 1 plays its slow build so wonderfully, and writer Sasha Hails allows all the pieces to settle into place while slowly allowing tension to build, and break. Those minimalist sequences where the Lady Lyzera visits Simeon Swann (Tom’s newfound long-lost granddad) in his dreams, are a festival of dramatic irony – for all his magical skill, he’s been away from the world for long enough that he has no frame of reference with which to recognise the Nekross, and that Lady Lyzera is therefore not to be trusted.

It’s an unfortunate confluence of circumstances that leads to Simeon’s inadvertent betrayal of the Key of Bones and its significance in closing or opening the tears in the Line of Twilight, but it’s also the piece of damning evidence that would seem to justify Michael and others’ mistrust of him.

I find myself identifying with everyone’s conflicting motivations here: Ursula’s mixture of reluctance and concern, in spite of apparently still loving Simeon even after years of absence; Tom, who is fond of his new grandfather as a very different (grand)parental influence; Michael, who knows Simeon only as the man who abandoned his wife and mother-in-law; Randall Moon, guarded and fiercely protective of Ursula; and Simeon himself, prone to making ill-considered and dangerous decisions, but always with the best of intentions.

Junix Inocian is joyously camp as the Quest Master who meets our heroes (and enemies) in their search for the Key, though admittedly a touch useless if he’s content to allow Tom and company to win the series of challenges, only to have the Key immediately snatched and smashed by Lyzera in order to enact her nefarious plan.

Seriously Quest Master, you’ve been at this for hundreds of years. You had one job! At least her reveal as a sorceress to Varg is a satisfying turn of events, and we’re finally seeing the culmination of almost an entire season of diabolical plotting.

It’s nice to see that Simeon is at least able to redeem himself by volunteering to return to the Neverside, but I rather would have liked to see more of his efforts to re-integrate himself into Tom’s family. Oh well, maybe that’s a story for another season, I suggest while pointedly smiling in the direction of the writers.

As a story, it feels less like a singular unit in itself and more of a series of linking elements to bring together what will be the thrust of the finale, but it certainly was good fun.

Aired at 5pm on Monday 17 November 2014 and 5pm on Tuesday 18 November 2014 on CBBC.

> Read more by Sami Kelsh on her website.

What did you think of the story? Let us know below…