McKinnon cuts a romance set among Australians fighting in PNG, with the stories of key figures working on the Manhatten Project, and a tired Japanese family to weave a story of the war.
While the connections between the stories in Japan and Los Alamos do not need to be spelt out - we know where this is going, the sections set in PNG feel a bit like a different story altogether. This isn't exactly bad - I think these are among the strongest sections of the book and the choppy structure works to give a sense of time passing and dislocation - but I did want, perhaps, a clearer connection than just 'war'. Partly, I suppose, they may have been there to give voice to the horror that so many of the Mahatten Project scientists kidded themselves they were ending.
I am not, it must be said, in the mood for Oppenheimer. I read this one alongside Kelly and Zach Weinersmith's excellent non-fiction deconstructing the fantasy of Mars cities, a project funded by meglomaniacs with a thing for Oppenheimer, which possibly made this the abiding schtick. But it feels as if we have rotated around this story so many times, and it never fails to make me furiously sad or sadly furious. McKinnon is smart to set the story in 1945, a time when it was not arguable that the atom bomb was needed to stop Hitler, and by which stage stopping the project would come at a very high personal and professional cost. Her characters twist in the wind, debating whether to share the intelligence with the soviets, a way perhaps of minimising the danger of atomic power by sharing it. It is hard to have sympathy, I have always found, for such brilliant people, many of whom took brave stances for others facing discrimination, who somehow pretended to believe that you could develop a weapon of mass destruction for peace*. 
The PNG section, while filled with the misery of stalking pesitilence, terrified jungle warfare and sexual violence, feels like the slower burn of the stories, centered on a gentle love story between two people slowly falling apart in the horror and yet detirmined to hang on to humanity and each other. It isn't something new, but McKinnon does it well and it provides welcome moral simplicity from the agonising at dinner parties and scenic drives in New Mexico.
I didn't love that few of the characters of colour survive, especially in the PNG storyline. It does start to feel a tad as if they must die so that our heroic couple can have some moments of clarity. I do think there are dangers in white Australian writing about countries Australia has colonised in various ways, in avoiding perpetuating a view that their lives are background to Australian dilemmas. And while Hiroko and her family are drawn compellingly, it can feel as if this family exists to show the consequences of other characters' choices as well.
Overall though, an engaging read, which succeeds in exploring the enormity of war.

*In my recently read Playing with Reality by Kelly Clancy, she tells of how HG Wells produced a war game for children hoping that the horror of the calculated casualties would put them off war forever. One of its most fervent players was a young Winston Churchill, so you can see how that turned out.