When Sarah was 10 years old, she got a heart transplant. Soon after, her mother decided to find out more about the person who saved her daughter's life.
Lucy, a 28-year-old girl with cystic fibrosis, meets the "Bike Girl," who has the same disease, in an Internet chatroom. They are both, against the advice of friends and doctors, trying to get pregnant, and they find that they have a lot in common.
Brady Udall tells the story of the time he helped a stranger get his car out of a ditch. In exchange, the man promises to help him any time, for any reason—legal or not.