The choices are bad and worse. Who lives?
And then it's Castor's turn to die.

Josephs, the prior Resistance Commander, engaged a Unity fleet in an attempt to keep his Resistance from moving to the successful and active Grey Fleet. After he was captured and gave the Unity all the information he had about Castor and Genine, the Unity killed Josephs and all his ships. Modifying their ships to compensate for the known factors, that fleet engaged Castor and the Greys.
After the Greys impossibly managed to regain the advantage, the G escaped with the kitacore Castor had brought, along with some of his DNA.
A Castor-clone was grown and Grimmerized.
Castor and the Prophecy Response Team are closer to finding the Adversary with each challenge they face. But the super-intellect Castor-clone has planned and prepared, leading them to find him.
Executing Castor will be the first step in completely exterminating the pestilence of the Resistance, along with all of the non-Unity from the Universe.

Haunter Grey Execution starts immediately after Prophecy and completes the Destiny Trilogy, a story so enthralling it will not let you go.