Ally by Karen Traviss
Powerful, award-worthy author Karen Traviss returns to the explosive "Wess'har War" novels, in her most accomplished, action-packed story yet. As the Isenj civil war continues, the ghosts of Shan Frankland's past come back to plague her present. For the c'naatat genie will not go back into the bottle, and the implications are boundless. Once infected, c'naatat carriers are virtually immortal...and the process cannot be reversed. And asking for help from a vastly superior alien military means that the changes they bring may or may not be what you initially asked for. As pressures mount from every side, Shan must make a difficult decision - leave the new life she has created on F'nar to save Earth from itself, or turn her back on humanity forever?