The Earth Federation and the League of Sovereign Systems have defeated the Ascendancy at the Battle of Triumph, but the former enemies are a long way from winning the war against their mutual foe. Earth is still under siege, and the ships defending it are critically low on fuel. Squadron Leader Mason Grey and Osiris Squadron will play a key role in breaking the Ascendancy’s blockade of Earth and getting the homeworld's defenders the relief they desperately need. Meanwhile, Lieutenant Jessica Sinclair continues her investigation into the mystery of the Ascendancy's origins. Thanks to the capture of an Ascendancy mothership at the Battle of Triumph, she may have the clues she needs to discover where the Ascendancy came from. And more importantly, reveal why they attacked Humanity in the first place.