Exodus: The Helium Sea Peter F. Hamilton

For millennia, the Crown Dominion has been at relative peace, with the Celestials in control and the human population little better than serfs. But now the Crown Dominion is facing a crisis of epic proportions – one that could change the balance of power in the Centauri Cluster forever – as an exiled faction that has been waiting for seven thousand years beyond the Helium Sea has returned to wreak their vengeance.
For Finn and his human allies, who have ended up at the centre of this conflict either through circumstance or manipulation, this is an unprecedented opportunity. If they can band together, they may be able to outwit the Celestials and finally earn their fellow humans a place of independence and power in the Crown Dominion. To achieve this, they must first locate and master ancient artefacts of immense power that could give them a much-needed edge in the conflict ahead. And all while ducking the forces that are determined to knock them off the board for good.