Max Edelman was just 17 when the Nazis took him to the first of five work camps, where his only hope of survival was to keep quiet and raise an emotional shield. After witnessing a German Shepherd kill a fellow prisoner, he developed a lifelong fear of dogs. Beaten into blindness by two bored guards, Max survived, buried the past, and moved on. But when he retired, he needed help. After a month of training, he received Calvin, a devoted chocolate Labrador retriever. Calvin guided Max safely through life, but he sensed Max's distance and reserve. Calvin grew listless and lost weight. Trainers...