This book was sent to me by the publisher, Hachette Australia, at no cost. It’s due out on August 11; RRP $32.99 (trade paperback).

This is a debut novel – which doesn’t mean Johnson has never written a novel before, of course, just that this is the first one to be published. And it’s pretty great.

It is unclear to me exactly when this is set; some time in the future, but not unimaginably so. It’s also unclear where this is set – I just assume it’s meant to be America because as an Australian, I assume most novels are set in America unless they’re evidently in the UK somewhere. (Realising the setting is Australia, or somewhere other than the US or UK, is often a very surprising moment, unless I’ve gone in knowing the story is deliberately set in, say, Nigeria.)

Anyway. Both the when and the where are basically irrelevant to the story, because the most important where is that most of the action is on Earth Zero. This is a world where not only have parallel universes been discovered to be real, but someone has discovered how a person can travel between them.

These sorts of stories have happened before (says the fan of Fringe) but the particularly clever thing that Johnson does is the caveat that you can only survive traveling to a world where your dop (doppelgänger) is dead.

Barring unfortunate accidents, you know who makes the most valuable traversers, therefore? who are the people able to access the most worlds? It’s the people whose survival to adulthood is unlikely. For wealth, ethnic, gender, location, and other systemic reasons. Those who grow up in areas with a lot of violence. Those from families or suburbs or countries with widespread violence. Those who, in the general course of a capitalist world, are seen to have little real value.

This is a brilliant twist, and I love it. And I also love that Johnson doesn’t present this as meaning that those people suddenly get great lives. Instead, the protagonist – Cara – is always aware of the fact that she could be replaced by robots when that tech works; that the people who were born in the nice town, as opposed to where she grew up (very much not-the-nice town), look down on her or fear her. Her existence is precarious despite her value to the company.

So partly the narrative is about Cara and her navigation of the two worlds – the rich and the poor, in brutal essence – that she straddles. It’s also, of course, about literally moving between worlds, and seeing how different choices have led to different outcomes – on a societal level or an individual one. Unsurprisingly Cara ends up being more involved in one of these other worlds than is appropriate by company standards, and that has knock-on effects for that world as well as her own, which is the bulk of the story.

The novel has little interest in explaining how moving between the worlds works; the science and technology are irrelevant to the story. Instead, Johnson is interested in the people: what secrets are kept and why; how relationships work; why certain decisions are made, and how they change human interactions. I enjoyed this focus a lot.

One aspect didn’t quite work for me; there’s an undercurrent of science v religion, especially in the way that Cara talks about the experience of moving between worlds – as a goddess allowing her to do so. I didn’t feel like this really fit the rest of the story. However, this does not detract from the rest of the story; it just felt undeveloped, like there could have been a bit more discussion of the possible mysticism of moving between worlds; it’s just not there as much as I think I expected.

Overall, this was a very enjoyable book, and I hope that Johnson is able to write many more in a similar vein.