Zenn Scarlett is a bright, determined 17-year-old girl training to become an exoveterinarian, specializing in the treatment of exotic alien life forms. Her novice year at the Ciscan Cloister Exovet Clinic on Mars will find her working with alien patients. But after a series of inexplicable animal escapes from the school and other near-disasters, the Cloister is in real danger of being shut down by a group of alien-hating officials.