The story takes place a little after the events of Silent Threat: Reborn.
The official synopsis.
Between the Ashes tells the story of mankind after the Shivans have been defeated and the Lucifer destroyed. The stage is set by the GTI rebellion near the end of the Great War. Without a home, mankind wanders across the stars aimless and without purpose. Where do we go from here? Are the Shivans still out there? Who else might lurk in the universe seeking our destruction and how do we prepare? These are the questions everyone is asking.
The losses to the Shivans and the crippled state of the GTA from the Fourteen Year War has caused many to lose faith in a unified government. And the Hammer of Light has become a dangerous terrorist group, but to what end?