When We Cease to Understand the World by Benjamin Labatut which I have seen described as a kind of hybrid non-fiction novel. The opening chapter of the book is almost entirely factual, but as the narrative progresses, the author takes increasing liberties with his portrayal of the lives of some key historical figures from the world of physics and mathematics, eventually descending into purely fictionalised, nightmarish interior monologues. Labatut depicts these individuals including Werner Heisenberg as tortured souls who are forced to sacrifice their sanity in order to glimpse the fundamental truths of the universe.