Traverser 

The sun has died, forcing mankind to retreat towards what little heat remains beneath the planets surface. Humanitys last bastion, Brimstone, is a city literally divided into upper and lower classes, both controlled by the all-powerful Raven Corporation. Raven Corp also controls the citys breathable air, with the wealthy Upper City getting far more than its fair share… Young Valerie Bennett has just passed the test to become a Traverser; a new kind of peacekeeper with the ability to travel between the Upper and Lower cities of Brimstone. Join her on a mission to reveal Raven Corps sinister secrets, uncover years of lies and propaganda, and discover the most dangerous thing in all of Brimstone: the truth.