A surgeon and a scientist have been secretly trying to transplant the brain from one hog into another. Soon after their first success, they have a golden opportunity to save a human: a 70-year old professor of history is mortally injured in a car accident, but her brain is unhurt; a 25-year-old has severe head trauma, but is otherwise unscratched. The professor, Louisa, awakes in hospital inside the body of Yvette, the youth. She realizes immediately that the scientists have not thought through what her life will be like, but she valiantly tries to adapt. Louisa, as Yvette, is alternately in danger, lonely, resolute, and delighted, and she's always perceptive.