The Plague of Dawn — Christopher Bailey

The Highlord had been defeated. Allie and her friends could all return home and pursue lives of peace at long last. Dav and Artus could return to rule the Sy'hli Empire, Tic could return to the jungles of Ayaran, and Allie and Imber could reunite with their families. Even Raith could, for the first time in his life, pursue whatever life he chose. 

But before peace could become more than just a happy thought for tomorrow, the Highlord's final act once more brings pain and terror to the galaxy. A devastating virus had been unleashed, capable of destroying all life in the galaxy and beyond. Threatening to tear the group apart, sabotage from within undermines the very foundation of their friendship, and brings the galaxy to the brink of another interstellar war. And behind it all, an enemy they all thought gone forever. 

With the Coalition divided, the Resistance broken, deadly assassins that even the Maruck fear in close pursuit, an unstoppable virus spreading across the galaxy and all life hanging in the balance, Allie faces her greatest fear as her new-found power begins to fall under the control of a being beyond anything she could possibly imagine.

The galaxy's last hope rests with the Starjumper, who must accept that for all life to survive, one of her friends must die.