XENOGENESIS is a tale of change; inexorable and inevitable. Human beings are always craving change but when it comes it is frightening . . . Sometimes to the point that we would prefer death. Pat Dalworthy is a tracker, ex-pilot cadet in space corps and a dabbler in physics. As a Tracker, a hunter of people who would rather not be found, he is the best there is in inner system and, to hear him tell it, outer system, too. One of...