Alison Leigh Powers, 11, and best friend, Mitty, look for a secret hiding place in an old mansion. They learn the history of the house from the builder's granddaughter, who is now ninety-two years old. She tells them that her grandfather's first wife mysteriously disappeared. Alison and Mitty find old letters in a trunk, and do research in the mansion's library with the help of Alison's mother, who works there as a librarian and book conservator. When they piece together what really happened to the first wife, they discover more than they ever expected--or wanted--to know!