The enemy is advancing quickly while the Coalition falters. The time for desperate measures is at hand. One possible solution lies in an ancient and mysterious alien device known as a Portal-a doorway into Earth's past. The Earth Security Council believes that if a key event in history can be prevented from ever happening, then the ultimate outcome of the war can be changed in the Coalition's favor. Theoretically. But theories have a way of being wrong. With no way to predict the results of such a mission with any certainty, Admiral Icarus Hansen, chief of Solfleet Intelligence, a man haunted by actions he has taken in the past, must decide whether or not to go forward with the mission anyway, knowing that whoever goes might never be able to return home.