Series note: this is the third novel in the Russell’s Attic series, featuring mathematical action hero Cas Russell. You should start with Zero Sum Game for the full picture; parts of this story would make much less sense without that background, so I wouldn’t recommend reading this series out of order.
The little charge blew the safe open with a satisfying pop. The only thing inside was the flash drive I’d come for; I tucked it into my inside jacket pocket, thinking in an idiotically conceited fashion that this job had been a piece of cake.
Then I turned around and found myself facing three assault rifles.
Cas doesn’t find life easy when she’s between jobs, so she’s almost relieved when Arthur asks her to work on behalf of an old friend… though she’s less impressed when it turns out that the friend in question, a maths professor whose work has been stolen, didn’t actually want their help. When Cas hears what’s in the notes that have been taken from Professor Halliday, however, she immediately understands the consequences: this is a proof that would turn modern cryptography on its head.
It’s always refreshing to read a thriller written by someone with an understanding of basic physics, since the genre is so often plagued by jarring inaccuracies; this book goes a bit further. Not only does Cas, the first person narrator, have equations running constantly through her mind, but the plot revolves around the discovery of an efficient factorisation algorithm, and the possibility that P might equal NP after all. Cas is a mercenary, accustomed to shooting her way out of trouble, but this time she’s up against some serious opponents, including government agents. And if they can’t retrieve the original of Halliday’s proof, national security demands that they at least reconstruct it.
I’ve been a huge fan of this series from the beginning, and some of the series-level plot elements are really starting to pick up speed. Cas isn’t great with people and evidently doesn’t have much practice at maintaining friendships, yet she cares deeply about Arthur and Checker and Pilar, making it all the more painful when their friendship begins to show cracks under pressure. Yet Arthur’s relationship with Sonya Halliday, for all its awkward monments, gives a hopeful model of unconditional (and platonic) love. Cas’s mathematical abilities have helped her out of tight spots throughout the series, but it’s only in this book, with its advanced proofs, that we start to see any hint of a limit to her natural skill. As for the question of how she came to have such a unique talent in the first place — well, I’m hoping that might be uncovered in the next book, as I now have more questions than ever.
Root of Unity is published at the end of the month, and is currently available to preorder.