She has an admittedly odd hobby: She and her German Shepherd have spent the last seven years searching for the dead. Solo is a cadaver dog. What started as a way to harness Solo’s unruly energy and enthusiasm soon became a calling that introduced Warren to the hidden and fascinating universe of working dogs, their handlers, and their trainers. Her new book What the Dog Knows: The Science and Wonder of Working Dogs chronicles her experiences training Solo to be cadaver dog, stories about other working dogs and the people who love and manage them, and of her research into how dogs smell and why that matters.