Maths professor Andrew Martin has been "taken by the hosts" and replaced by an alien who takes his form. The Vonnodorian's are a race who believe Martin's solving of the Riemann hypothesis will lead to human space travel, and so the solution must be destroyed, along with anyone else Martin divulged the details to.
Haig sets out his stall in the preface. Through these alien eyes he will reveal to us what it is to be human. His alien will report to his fellow Vonnodorian's about us. He will gently poke fun at the ridiculous things we humans do, but he will also illuminate the essence of who we are. In pretending to be human, Andrew Martin, or rather, the alien Andrew Martin, will discover that no matter how evolved and superior his own race, nothing compares to human love.
In snappy little chapters the alien relates the story, which ostensibly is about him tracking down people who may know of Martin's Riemann hypothesis breakthrough, but of course is merely a vehicle for Haig's observations. He's a thoughtful and skilled writer, what could be trite bite sized homilies are actually resonant and wonderful pieces of wisdom.
I don't want to spoiler things with any further plot development, but I do want to share two brilliant quotes, so as to entice you to buy this for yourself.
Firstly funny/true, "I realized that if getting drunk was how people forgot they were mortal, then hangovers were how they remembered."
And then profound, "Your mind is a galaxy. More dark than light. But the light makes it worthwhile. Which is to say, don't kill yourself. Even when the darkness is total. Always know that life is not still. Time is space. You are moving through that galaxy. Wait for the stars."
Those nine sentences may just be the most beautiful and important words I've read.
5 hours ago