This looks like a great series that I plan to check out in the near future!
More than three thousand years ago Angels saved humanity from destruction, but Earth was lost. The Angels spread humanity across the stars and ruled the universe for twenty-five hundred years. Then they vanished.
Angelolist Rachel Jordan has come to the hellish world of Gehenna in search of a lost relic said to hold all the knowledge of the angels. But other factions seek it for themselves, and religious zealots will stop at nothing to keep it safe.