Species Imperative

With the alien Dhryn cutting a pathway through the inhabited spaceways-bringing about the annihilation of many of the races who have the misfortune to lie along the star trail they are following-time is running out for all sentient life-forms. Can biologists Mackenzie Connor and Emily Mamami solve the riddle of the Dhryn before their part of the galaxy becomes as dead as the mysterious region known as the Chasm?