Illuminea - Amie Kaufman & Jay Kristoff - Paperback

The Illuminae Files, Book 1 of 3, finished series

The year is 2575, and tow rival mega-corporations are at war over a planet that's little more than an ice-covered speck. Now, with enemy fire raining down on them, exes Kady and Ezra, who are barely even talking to each other, are forced to escape on the evacuating fleet. 

But their problems are just beginning. The fleet's AI has gone crazy, a deadly plague has broken out on one of the ships, and nobody in charge will say what's really going on.

As Kady hacks into a tangled web of data to find the truth, it's clear only one person can help her: the ex-boyfriend she swore she'd never speak to again.