The Redemption Engine (Unabridged‪)‬

When murdered sinners fail to show up in hell, it's up to Salim Ghadafar, an atheist warrior forced to solve problems for the goddess of death, to track down the missing souls. In order to do so, Salim will need to descend into the anarchic city of Kaer Maga, following a trail that ranges from hell's iron cities to the gates of heaven itself. Along the way he'll be aided by a host of otherworldly creatures, a streetwise teenager, and two warriors of the mysterious Iridian Fold. But when the missing souls are the scum of the Earth and the victims devils themselves, can anyone really be trusted?