Ethaniel goes to meet Thorber alone. He returns with a high fever and is almost uncontrollable. Thorber realizes that he is not ill but is reverting back to his true Therian state and if he does that the atmosphere on Earth will kill him! Thorber takes him and Laura to a friend of his, Dr Tremblay, who may be able to help. While the doctor tries to keep Ethaniel alive Laura and Thorber follow the only clue they have, a matchbook and a name written on it. To save Ethaniel from the virus that is causing his change they need to find out who infected him in the first place, and do it in the next 24 hours.