When I decided that the final book would be all about Jack and his character and how he became the hero we know, I felt it was the perfect time to refer to her again.

The quadrilateral maze has to be one of your most brilliant, complex creations, Matthew. How did you come up with it?

I just wanted the Supreme Labyrinth to have one totally wild maze and the rotating maze was it.

Coming up with it wasn’t so hard. It was describing it that was tough! Figuring out how to describe a wall becoming a floor, or a blockhouse going upside down took many, many rewrites.

Then we finally get the answers we’ve been waiting for when Jack meets the Gold Colossus and learn the secret of the Lifestone, the seven worlds . . . how satisfying was it to finally write this scene, to reveal everything?

Yes, this was a very satisfying scene to write. It was something I’d thought about back when I wrote The Six Sacred Stones. (It’s funny, the whole series really began with that book. Seven Ancient Wonders gave me a taste of the world I was creating, but it was really while writing 6SS that I truly sat down and contemplated the question: who built all these ancient sites and why?)

I love all the mysterious ancient places in our world and I’ve visited many of them. The inexplicable nature of them just intrigues me. The Great Pyramid. Stonehenge. Chichen Itza.

It’s this kind of inherent mysteriousness that gave rise to the Gold Colossus’s words and the idea that we humans, with all our tribalism and wars, are failing at some kind of celestial test that was left here for us.

It’s a close fight right until the end, and the odds are never in our heroes’ favour—but they are triumphant. How did you go about deciding fitting ends for Ezekiel, Dion, Rastor, Mendoza and Sphinx?

This is a good question. It’s all about comeuppance. About these villains getting what they deserved.

Ezekiel, the woman-hating monk, of course, had to be killed by a woman, and so that honour went to Zoe.

Dion—who had been doing dastardly things since 4LK—had to meet his match in Lily. And Lily had to defeat him without Jack’s help. This was always going to be her moment, her triumph over him.

Cardinal Mendoza was always going to die at the hands of the Gold Colossus. He’s a snivelling toady, a conniving manipulator, and thus unworthy. He was always going to be there for the shocking moment where it seems that the colossus has condemned Jack to die.