I have a confession to make. When I finished the first chapter of Ninefox Gambit, the debut novel from noted short fiction author Yoon Ha Lee, I thought that was all I would read. It wasn’t clicking with me. I found the world confusing, the action gruesome, and the pace difficult to keep up with. I could recognize that novel’s quality, and the originality that Lee is known for, but other books beckoned, and there was an easy, lazy whisper at the back of my head. “It’s just not for you,” it said. I listened, and moved onto another book.

Yet, here I am reviewing it.

Funny thing happened. That whisper was replaced by another voice—one that kept speculating about Ninefox Gambit‘s opening salvo. Then a couple of readers I respect began to rave about the book, and that voice in my head grew louder and louder, until it was impossible to ignore. The last time something like this happened was with Ann Leckie’s Ancillary Justice, which I found tough going for the first act, but then adored by the time I hit the final page. So, I listened, and, boy, am I glad I did. Ninefox Gambit asks a lot of readers when they pick it up, but damn if it doesn’t repay in double by the end.

It’s said that sufficiently advanced technology is indistinguishable from magic, an idea that Lee embraces in Ninefox Gambit. Reading Ninefox Gambit reminded me of reading a wholly different and surprising novel: Steven Erikson’s Gardens of the Moon. In both, you’re thrust into a volatile, complex world governed by physical laws and systems for which we have no real world corollary, but are expected to keep up anyway. No hand holding. No baby steps. This is obviously military SF, but unlike a lot of the genre, which is rooted in hard science, the technology in Lee’s universe seems to have no limits, and relies on a “calendrical” mathematical system that is beyond our understanding of physics—rendering it, essentially, magical. Though it relies on its own intricate mathematical formulas, it’s all hidden from the reader—no complex explanations of super-position or astrophysics to be found. The end result isn’t much different than a military fantasy that features magical weaponry, mass army-affecting spells, and terrifying undead generals. It’s a unique combination, and Lee pulls it off with such confidence that it’s a pleasure to straddle that line, to see what he comes up with next. And, boy, are there some high concepts by the time you hit the riveting finale.

At the core of the novel’s central conflict is something called “calendrical rot,” which is being abused by a set of heretics to turn the nature of the surrounding technology to their advantage. “WTF is calendrical rot?” you ask. Good question. In fact, I wasn’t quite sure myself for the first half of the novel, until I stumbled across this speculation from a review on Goodreads:

What’s a calendar, you ask? Oh, it just happens to be a society-wide mental and mathematical consensual reality engine that requires, (I believe,) the rigid mindsets of all the people under it to alter reality.

A theory that’s corroborated by Lee’s short story, “The Battle of Candle Arc,” published by Clarkesworld, which is set hundreds of years before Ninefox Gambit:

The heptarchate’s exotic technologies depended on the high calendar’s configurations: the numerical concordances, the feasts and remembrances, the associated system of belief.

Finally, Jedao explains the concept of games to Cheris, and, in turn, sheds light on the mechanics of calendrical war and rot:

“According to the Shuos,” Jedao said, “games are about behaviour modification. The rules constrain some behaviors and reward others. Of course, people cheat, and there are consequences around that, too, so implicit rules and social context are just as important. Meaningless cards, tokens, and symbols become invest with value and significance in the world of the game. In a sense, all calendrical war is a game between competing sets of rules, fueled by the coherence of our beliefs. To win a calendrical war, you have to understand how game systems work.”

So, the heretics (the so-called “badguys”) are twisting this “reality engine” by breaking away from the hive-mind agreement that gives the government, the aforementioned heptarchate (which is the hexarchate by the time Ninefox Gambit begins), authority over the people and high-level technology. By doing so, they literally change the physical rules of warfare within their realm of influence, which centers around the Fortress of Scattered Needles. They’re trying to change the universe by recognizing that the near-holy calendrical system is more or less a mass delusion, that it can be abused, and is, in fact, a tool for the government to control its citizens. This calendrical system is so baked into societal day-to-day operations that it is no more explained to the reader than the physics of electricity would be in a near-future science fiction novel. So, yeah, it’s a lot to take in. Still confused? So am I. And therein lies the novel’s most challenging aspect. But that’s okay, and I’ll tell you why.

Military SF is often morally complex—a lens through which we examine the personal, political, and cultural impacts and costs of war, which itself is one of humanity’s most powerful engines. Ninefox Gambit goes above and beyond this, matching its emotional complexity—and, boy, is it packed with rich interpersonal relationships—with equally labyrinthine and dense world building. Lee’s never complex just for complexity’s sake, but, most of the time, the reader has to meet Lee more than halfway. Lee respects his reader, and assumes, in a very bold way, that they’re keeping up, that they’re willing to put in the work. He’s the hare, you’re the tortoise. Except, instead of taking a nap at the finish line, he’s waiting there, asking what took you so long. Due to the complexity of Lee’s worldbuilding, offset somewhat by the delicacy of his relationship-building, and a surprising amount of humor for an otherwise grim novel, a universe comes to life that feels at once human in its goals and emotional conflicts. At the same time, it often feels utterly alien in its reliance on calendrical whatnots, dead generals living in other soldier’s shadows, cindermoths, and literal face-melting weaponry. It’s a difficult balance to achieve, and Ninefox Gambit struggles a bit out of the gate, but once it finds its stride, it becomes impossible to put down.

A major reason Ninefox Gambit is able to overcome its complexity (an aspect that I’d rarely use in the same sentence as “page turner”) is the intricate relationship that forms between its two principal protagonists: Kel Cheris, a front-line soldier elevated above her rank due to her mastery of complex mathematics, and Shuos Jedao, an insane undead general brought out of the freezer to lead the impossible task of reclaiming the Fortress of Scattered Needles. As you might expect, Cheris and Jedao are polar in their personalities, and many of their core ethics and motivations appear very different on the surface. Cheris is a bred-and-born solider, used to following orders to the letter, and Jedao is best known for a treasonous massacre during which he eradicated the army under his command. Not everything is as expected, however.

Jedao, the immolation fox, genius, traitor, mass murderer, is layered and at times at odds with what the reader, and the characters surrounding him, are led to believe. This introduction to his history sets a chilling tone:

Three hundred ninety-nine years ago, General Shuos Jedao was in the service of the Kel. Because he had a reputation for winning unwinnable fights, they assigned him to deal with the Lanterner rebellion. In five battles, Jedao shattered the rebels. In the first battle, at Candle Arc, he was outnumbered eight to one. In the second, that was no longer true. The rebels’ leader escaped to Hellspin Fortress, which was guarded by predatory masses and corrosive dust, but the heptarchs expected that Jedao would capture the fortress without undue difficulty. Instead, Jedao plunged the entirety of his force into the gyre and activated the first threshold winnowers, known ever since for their deadliness. Lanterners and Kel alike drowned in a surfeit of corpselight. On the command moth, Jedao pulled out an ordinary pistol, his Patterner 52, and murdered his staff. They were fine soldiers, but he was their better. Or he had been. The scouring operation that had to be undertaken after Jedao was extracted cost the heptarchate wealth that could have bought entire systems, and many more lives. Over one million people died at Hellspin Fortress.

But, as Cheris slowly begins to understand, controlling the narrative that surrounds you is a tool like any other. Due to the symbiotic relationship between Cheris and Jedao (he lives in her shadow, speaks directly to her mind, and can read her thoughts if she’s not careful), there’s a fascinating blurring of their personalities. By combining their strengths, Jedao (military strategy and charisma) and Cheris (combat experience and complicated mathematics) become something greater than the sum of their parts—something with the potential to upset the calendar. Of course, Jedao has a secret, and as its magnitude is slowly revealed, the stakes become clear, and the potential for future books in the series grows more exciting.

Lee is reflective and no-holds-barred in the way he examines the coalescing of Cheris and Jedao’s personalities. It’s impossible for them to share responsibilities and, literally, a body, without bleeding into one another. It’s a keen examination of the way personalities can warp around the people surrounding you. Cheris is the ying to Jedao’s yang, but together they are something wholly more. So much of Ninefox Gambit is about exploring truth, what you believe about yourself, what you believe about the world around you, and this leads to some fascinating moments between Jedao and Cheris, who see the world very differently from one another. They both have something to offer the other, though, which together makes them stronger, or, at the very least, more driven.

“You don’t sleep,” Cheris said, remembering. “You don’t sleep at all. What do you do in all that time? Count ravens?” Jedao was silent for so long that she thought something had happened to him. Then he said, “It’s dark in the black cradle, and it’s very quiet unless they’re running tests. Out here there are things to look at and I can remember what colors are and what voices sound like. Please, Cheris. Go sleep. You will never realize how valuable it is unless someone takes it away from you forever.” “You’re only telling me this to get me to do what you want,” Cheris said. “You’ll have to let me know how that works out,” Jedao said. “Something’s bound to go wrong in the Radiant Ward, and they’ll need you.” “Need you, you mean.” “I said what I meant.” Cheris looked around the dueling hall, then let her feet carry her back to her quarters. Before she lay down, she asked, “Are you lonely when I sleep?” He didn’t answer, but this time she left a small light on.

Jedao is a literal, physical violation of Cheris’ privacy, of the right to her body, and yet she still comes to form a respectful professional relationship with him—to care for him, and to show concern for his comfort. These contemplative, almost tender moments between the two of them, who each have a tremendous amount of blood on their hands, are almost startling. They are soldiers, but, like every soldier, they’re also human, with individual desires and motivations. Dreams.

This is a book full of death, but also life.

Naraucher wasn’t crying when his company reached the gate’s shriveled remnants, passing through the smoke-memory of people reduced to phantasms of number. But his eyes hurt. Ula’s company had burned up evaporating the gate. He could only do his part: fight through the breach they had won for those who followed.

As anyone familiar with Lee’s short fiction would expect, the prose in the novel absolutely sings, putting it above the average military SF, which can often use simple prose as a method of cementing the gritty, clipped reality of life as a soldier.

An example:

It was an eerie building, full of walls that sang your breath back to you as poetry, and light that coruscated like flowers. Beautiful, if you wanted to feel that beauty hid unhealthy secrets from you.

And:

You could almost mistake this for peace: the wind, the grass, the hills. The way the light snagged on the edges of leaves, and changed the colors of stone and skin and trickling water.

Lee knows that if the fate of the world is at stake, the reader has to care about that world, so he uses language as a way to reveal a beauty that can be found even in the depths of an interstellar war. He builds more in a couple of sentences than some authors manage in entire novels, and beautifully.

Ann Leckie’s Imperial Radch trilogy, beginning with Ancillary Justice, took science fiction fandom by storm a few years ago, and Ninefox Gambit is well-positioned to fill the void left by its 2015 conclusion. Both series are action packed and challenging in a way that requires a reader to be an active participant, but rewards such them generously. Don’t be put off by the opening chapter. Ninefox Gambit might not work for everyone, but for those itching for dense worldbuilding, a riproaring plot, complex relationships, and military SF with a deep imagination, it’ll do just the trick. Lee’s already shown he has the chops for short fiction, and now Ninefox Gambit proves that he’s a novelist to watch out for. This is military SF with blood, guts, math, and heart.

Ninefox Gambit is available now from Solaris Books.

Hugo Award winner Aidan Moher is the founder of A Dribble of Ink and author of Tide of Shadows and Other Stories. He regularly contributes to Tor.com, the Barnes & Noble SF&F Blog, and several other websites. He lives on Vancouver Island with his wife and daughter.