“This is a work of fiction based on real events,” says the author, and as such it’s weirdly disconcerting; you know the history, but you’re fuzzy on the details, and Labatut takes full advantage of that. The book kicks off with a mostly-factual account tracing the discovery of Prussian Blue to cyanide, poison, and its horrific use in the Holocaust; the author muses on the vibrant beauty of the color, and the stain that it left on history. The following stories go on to profile men of great brilliance, Schwarzschild and Heisenberg and Schrödinger among others, whose discoveries in math and science drive them to madness as they realize the destruction their ideas could wreak upon the world (or maybe, Labatut insinuates, they have to go mad to make these leaps of intuition at all). Their madness and visions are described with such lush prose that the feel of the text touches on gothic horror; fiction is woven so seamlessly into fact that you can’t draw a clear line between real and imaginary. The book swerves to end on a biographical, reflective tone, on which the narrator refuses to cut down a diseased tree; it is dying inside, but still tall and wide and of great sentimental value, and he does not wish to see the rot within. It functions as a kind of allegory: we can see and appreciate the outer structure of things, but if we dig too deeply, we may find ourselves revolted by what lies within, and the mere pursuit of that knowledge may bring it all crashing down around us.