Scientists are discovering what's behind the strong bonds that can form between dogs and humans. And few bonds are stronger than those between therapy dogs and the patients they care for. Bailey was the first resident therapy dog to work in a large Japanese hospital. Over his 9-year career, he's cared for thousands of children, comforting them as they face intractable diseases. The dedicated therapy dog is now ready to retire. But first he must help a young girl named Yui deal with a life-threatening illness.