Review: The Devotion of Suspect X

The Devotion of Suspect X was something I often saw in recommendation lists, but it was the unfortunate recent death of the author that led me to read it. Going into it, I expected a fairly standard ‘whodunit’. Instead, I found it less of a mystery of who committed the murder and more a mystery of why and how the cover up happened. This isn’t really a book about a man devoted to a woman he’s helping cover up a murder for. It’s more about a man devoted to math and logic themselves, who happens to apply that devotion to covering up a murder.

Devotion has many layers

“Which is harder: devising an unsolvable problem or solving that problem?”

That man covering up the murder is Ishigami, and the detective attached to the case is professor of physics Yukawa, also known as Detective Galileo. Yukawa once posed a question to Ishigami, on “Which is harder: devising an unsolvable problem or solving that problem?”, which is really a question about whether verifying someone else’s correct solution is as hard as finding the solution yourself. Ishigami is trying to turn this murder into an unsolvable problem, and Yukawa and the police spend the book trying to solve it. Ishigami talks elsewhere about how the kids in his class often look at a problem all wrong, seeing a geometry problem when it’s actually an algebra problem, and how his job is to expose that blind spot. It’s this exact mentality, applied to a cover up instead of a chalkboard, that eventually gives Yukawa the thread he needs to pull. Ishigami was a genius, but his devotion showed up in more places than just mathematics. His devotion to his parents outweighed his devotion to math itself, which is part of why he ended up teaching high schoolers instead of working at a prestigious university, and even there, he’s genuinely devoted. He explains to his students why math actually matters, and tries to make it land for them. When one student pushes back that a motorcycle racer doesn’t need calculus, that racers win on experience and instinct, Ishigami’s answer is one of my favorite passages in the book:

“I’m sure they do. But that isn’t true for the support team for those racers. They run detailed simulations over and over to find the best places to accelerate, that’s how they work out a strategy. And in order to do that, they use differential and integral calculus. Even if they don’t know it, the computer software they’re using does.”

The student keeps pushing, asking why not just leave the math to whoever makes the software, and Ishigami turns it back on him:

“But what if it was you who had to make the software?”

“Me? Write software? I don’t think so.”

“Even if you don’t become a software engineer, someone else in this class might. That’s why we study mathematics. That’s why we have this class. You should know that what I’m teaching here is only the tip of the iceberg, a doorway into the world of mathematics. If you don’t even know where the door is, how can you ever expect to be able to walk through it? Of course, you don’t have to walk through it unless you want to. All I’m testing here is whether or not you know where the doorway is. I’m giving you choices.”

I wish I had a teacher to convince me that well on the importance of math. That exchange shows just how devoted Ishigami was to math, and it extended to even teaching and preparing the youth to take math on. At the surface we’re led to believe his devotion is to Yasuko because he goes to great lengths and pains to cover up the murder. However, it’s become more clear to me that his devotion is to solving the unsolvable.

Blinded by his genius

That reframing also explains what I found frustrating about him. My first reaction was simple: why is this man voluntarily trying to cover up his neighbor’s murder? Yasuko was ready to just call the police and could plausibly have claimed self defense, and Ishigami’s involvement put her and her daughter in more danger, even as he took on the weight and burden of it himself. He’s clever at different turns of the investigation, but then I found myself thinking he was self sabotaging, or maybe self aggrandizing his own method to the point that it became self sabotage. Without giving too much away, some of the moves he makes to shift the investigation end up subtly pointing back at him, and for someone so logical, that felt entirely avoidable. In the end I don’t think I’m sympathetic to him so much as I think he’s severely flawed and lost, almost a caricature of what he portrayed himself to be, someone who couldn’t confront something head on the way Yasuko could and instead let his own arrogance decide things for everyone around him.

The relationship that actually carries the book, though, is Ishigami’s with Yukawa. Kusanagi, the actual police detective, felt run of the mill by comparison. Yukawa talks about Ishigami as a kind of Buddha, admiring him for that single minded focus on math and logic. While Ishigami is depicted as a loner during his university days but is able to stand and have respect for Yukawa because Yukawa is able to meet his genius intellect with a different perspective and sense of logic mixed with philosophy. The two of them took very different paths in life from the same starting point, and in the present day it becomes a silent chess match of minds, Yukawa testing theories against Ishigami about how the murder unfolded, at first only due to his proximity, but at some point suspecting all along that Ishigami is more involved than he’s letting on.

The effect of the cover up on Yasuko and Misato

A view on Ishigami that stuck with me was how Yasuko and her daughter, Misato, gradually change their opinion and thoughts about him. When the story begins, Misato has a sense of anxiety about Ishigami’s control over the situation, and Yasuko starts with a sense of debt and gratitude. However as time goes on, Misato develops a deep sense of loyalty for Ishigami from a place of fear, guilt and self-preservation because of what Ishigami could potentially hold over them. She even warns her mother that if she dates another man, Ishigami might be upset and leverage knowledge of the murder and cover up to blackmail them. Meanwhile from Yasuko’s perspective, she grows to see Ishigami as a jealous man ruining her chances of finding happiness. It’s interesting to see how their perspectives change: Yasuko’s from loyalty to resentment out of fear, and Misato’s anxiety to loyalty out of fear.

Early in the book Yasuko says, “Murder is murder. Everything else is just details,” and I thought it was really telling of her character. She really never wanted to cover up the murder. Ishigami calculates this when he offers to help cover it up, playing on her weaknesses, and in the end all in pursuit of his two selfish devotions: prospect of Yasuko in his life, and his own desire to create an unsolvable equation.

Overall this is like a 3.5 star book for me. Some things felt a bit fantastical and convenient, but otherwise I really enjoyed reading the ‘mystery’, and genuinely thought the reveal was clever. It’s a good twist on the mystery novel, and I’d recommend it especially if you’re looking for a mystery in a different setting than America, UK or some exotic setting.