Purists beware: Prosper’s Demon, by K. J. Parker, is not a tale of good versus evil. This is mostly a tale of not-as-bad and maybe-worse fighting it out, ostensibly for a greater purpose, but maybe just in a never-ending cycle of retribution. But as a world champion player of Petty Petty Princess, I can say that this is a feature, not a bug. Our nameless narrator wants to get rid of demons, and one demon in particular. He’ll avoid collateral damage if he can, but if he can’t…well. It might not make for a moral story, but it makes for an interesting one.

A quirk of birth and not a life of holiness left the unnamed narrator with the ability to expel demons from human hosts, a task he finds grimly satisfying. The demons can’t hurt him and they can only resist him to a certain extent, so he’s had a successful career. And if that career is littered with the bodies of those he couldn’t save in time…well, the church has always placed a higher value on expelling demons than on the lives those demons want to steal. If a number of people died in the course of his exorcisms, that still counts as a win. But his most recent case might end in his first L. How can he fight his old nemesis, currently ensconced in the body of a young prince, and also fight a strange new demon, who inhabits the body of the smartest man in the world?

This is indelibly K. J. Parker, by which I mean, it’s dryly funny, there’s a deep dive on a skilled profession (exorcism this time, and as ever, some engineering), some too-smart-for-their-own-good characters, and always, always some scheme that doesn’t fall into place until the last page. I’m not always a big fan of twists, but Parker is a goddamn gymnast: when he sticks that landing, you can’t help but want to cheer.

It’s always a bit easier to land twists in short fiction, since you really only have space for one great idea. It’s why I had mixed feelings on his Engineer trilogy (too many reversals eventually undercut the characters and the emotional weight—just like Game of Thrones), but loved Purple and Black and Blue and Gold. Those were novellas from the “dark days,” when big publishers hadn’t embraced ebooks and only small presses would take chances on shorter-form fiction (and the prices went up accordingly). Thank you, Tor.com, for changing all that.

But I digress. Prosper’s Demon, which is a perfectly modest and self-contained 112 pages, does indeed set us up for only one twist. It’s British in the way that the Freeman and Cumberbatch Sherlock is British: dry, self-deprecating, and so fast-moving that you can miss things if you’re not paying attention. But that’s part of the fun: what’s a red herring, and what’s a critical piece of information? I won’t spoil it, but I will say that I completely did not expect the direction it took, especially that twist.

Is the twist good? Yes, it’s unexpected and it’s perfectly in keeping with the narrator’s character. Is it satisfying? Well, that depends. If you agree with the narrator’s philosophy that demons are the greatest evil, then sure. If you’re not on board, the whole thing reads like the memoirs of an obsession, a cautionary tale rather than a triumphal one. It feels a bit hollow. But maybe that hollowness is part of the point, too. Our narrator tells us that “…only two things live forever, the instruments of darkness and works of genius.” It’s a lonely, empty world, only briefly illuminated by triumphs of art or science, and otherwise beset by demons that can literally never die. Life is a struggle, and living on your own terms—free of demons, or free of human judgments—is even more so. But in his unusual ending, Parker suggests that the struggle—which is ugly, and finite—might have its own merits. And regardless of how the narrator leaves you feeling, that’s a pretty good place for the book to land.

Prosper’s Demon comes out January 28.