Kris Longknife and her crew have just jumped the Wasp into an uncharted system when they encounter an alien Death Ball pursued by two battlecruisers. After Kris orders an end to the hostilities, the cruisers depart, but the alien insists on meeting with the leader of the human worlds. They are, they say, on a mission of peace.
Since the leader of the human worlds just happens to be Kris's grandfather, she is able to arrange the meeting-where the aliens reveal their message. They've come to warn of an unidentifiable force that is roaming the galaxy, obliterating everything in its path-a path now leading directly toward human space.
And in order to combat this unknown enemy, the commander of the Wasp will have to assume a very unfamiliar and dangerous role: Kris Longknife, diplomat.