Cassie is the daughter of two veterinarians, and shares their love for animals. She lives on a farm with her parents where her father runs a clinic to help injured wild animals. Only Cassie has a closer connection to animals: She can turn into them. But Cassie has qualms. Can she use the animals she loves to fight and sometimes kill other sentient creatures? Can she continue to feel what it's like to be an animal despite the costs of being an Animorph?.