Birds of Prey
David Drake
 The novel relates an episode in the life of Aulus Perennius, a middle-aged operative of the Bureau of Imperial Affairs, an agency which has evolved into an intelligence service over the life of the Empire. He is accompanied by his protégé Gaius, a dashing young cavalry officer with an unfortunate tendency to act without thinking, and an odd figure named Calvus, tall, slim, bald, incredibly strong, and rather clueless. (The story hints that Gaius is Aulus' biological son, but never makes a clear statement on the matter.) At the beginning of the story Aulus' own mentor, head of the Bureau of Imperial Affairs, has summoned him back to Rome on a matter urgent enough to pull him out of a deep-cover operation just as it was coming to its critical phase. At the direct behest of the emperor the Bureau has been ordered to provide Calvus with any sort of support requested, and Calvus has asked only for the services of the Bureau's best agent &mdash; requesting Aulus by name. Invoking the authority of the Bureau, Aulus orders an ancient trireme out of dry-dock storage to be outfitted for a trip to Cilicia in southern Anatolia, technically a part of the Roman Empire but at that time under the control of Odenath, to provide some unspecified service for Calvus. En route they are beset by pirates and other parties; the story of the journey takes up the greater part of the book. Calvus, though taken for a male, is actually a female (of sorts) sent back from the far distant future to destroy the seed creche of monstrous aliens who, by her time, have multiplied into millions, emerged from their underground creches, and are in the process of destroying the human race. As a desperate measure a set of six mutually telepathic sisters, including Calvus, are specially bred to be sent on the mission together. (The book hints that the future human race has evolved to be somewhat different from ourselves, and that the six sterile drone-like sisters are uncommon only in their preparation for this particular mission.) Calvus is the only one of the siblings to arrive at the proper time in the past; there are strong hints that the presence of a handful of extinct creatures such as dinosaurs and sabre-toothed cats in Aulus' time are a side effect of the unintentional displacement of the other siblings into the far distant past. The time-travel technology did not allow Calvus to take any weapons or other gadgets along, so she herself serves as the weapon. She has a limited ability to influence the thoughts of humans other than her sisters &mdash; which is how she induced the emperor to issue orders for the Bureau's cooperation &mdash; and at the end of the story she destroys the creche by self-destructing as a nuclear or thermal bomb. Before then, through her association with Aulus and separation from her sisters, she learns to experience her humanity almost in the way ordinary humans do.