Triggernometry is a novella about outlaws in the old west getting together for one last big score. Outlaws who are also mathematicians. Mathematicians who are outlaws because mathematics is illegal and its practitioners persecuted.

That’s it. That’s the concept. I have a feeling it came from a Twitter dare or something.

Somehow, Holborn makes it work. Probably because she’s clearly a very accomplished writer with an excellent grasp of pacing, prose, and characterisation. I haven’t read Nunslinger, though I’ve heard good things, but clearly this isn’t her first rodeo.

The novella tells the story of Mad Malago Browne, the one character I couldn’t find an exact historical mathematician namesake for. She’s down on her luck, trying to survive on illicit bookkeeping after having to give up her life as a gun- and protractor-slinging outlaw. But as a mathematician in this unforgiving land, you’re only one slip away from running for your life, so when her old partner in number theory and crime comes to entice her back for one last big payday, she reluctantly agrees.

It’s a familiar enough story – rounding up the gang, planning the heist, a bit of double-crossing – but the twists make it fresh and fun. As I hinted earlier, all her confederates are named after historical mathematicians, leading me down some interesting Wikipedia rabbit-holes (a definite bonus). Their mathematics makes them deadly gunfighters, like a Sherlockian super-power, which, if not always believable, is a lot of fun. Holborn plays it straight, too, wringing some drops of pathos from what should be an absurd concept, and the plot licks along like a wood-fired 4-4-0 (that’s not maths, that’s a locomotive). There are formulas at the start of each chapter and here and there in the text, and I can’t say I got all the references (I have a physics degree, not a maths one), but I appreciated them anyway. 

The setting is the Wild West, recognisable from any spaghetti western or video game, if not from history. It isn’t the United States for whatever reason, as there are no recognisable names and the geography is different, but that’s not important – it’s an alt-western, in that sort of steam-punky way of not being overtly fantastical but definitely fitting under the broader spec-fic umbrella. I’ve read a few other weird westerns, but those featured magic or monsters rather than mathematics, and this worked as well as any of them – and was definitely the best written. 

Overall, Triggernometry is an elegant solution to a formula few would find tractable. It’s punchy, action-packed, and embraces the central gag with winning sincerity. Definitely recommended, and, on this evidence, worth taking a look at the Nunslinger series as well.