Zenn Scarlett is a bright, determined, occasionally a-little-too-smart-for-her-own-good 17-year-old girl training hard to become an exoveterinarian. That means she's specializing in the treatment of exotic alien life forms, mostly large and generally dangerous. Her novice year of training at the Ciscan Cloister Exovet Clinic on Mars will find her working with alien patients from whalehounds the size of a hay barn to a baby Kiran Sunkiller, a colossal floating creature that will grow up to carry a whole sky-city on its back. 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. If that happens, Zenn knows only too well the grim fate awaiting the creatures she loves. Now, she must unravel the baffling events plaguing her school, before someone is hurt or killed, before everything she cares about is ripped away from her and her family forever. To solve this mystery - and live to tell about it - Zenn will have to put her new exovet skills to work in ways she never imagined, and in the process learn just how powerful compassion and empathy can be.