Echoes of Angels. Sins of Angels, #1

Professor Rachel Jordan committed the ultimate heresy: she dared to teach that the Angels were never humanity's saviours. For three thousand years, Angelic doctrine has shaped civilisation. The Redeemers-fanatical guardians of that doctrine-will stop at nothing to silence her. Branded a heretic and hunted by zealots determined to erase her beliefs, Rachel flees to the edge of civilised space. But she isn't hiding.
The only proof of her theories lies in the Sefer Raziel, a legendary lost book of the Codex written by a rogue Angel. Following its trail to a desolate former prison world, Rachel plunges into a ruthless criminal underworld to recover it. Instead, her search draws the attention of predatory megacorporations, puppet governments, and the Redeemers who refuse to let her escape. As rival factions close in, Rachel must trust dangerous allies and compromise the principles that define her if she's to reach the Sefer first.
Because failure won't just cost her life-it will condemn humanity to eternal servitude under the Angels' rule.