Dr. David Kalenberger is the head of a fertility clinic in Oklahoma City.

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.

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.

Chaya Lipschutz wanted to donate one of her kidneys to a stranger. But to save a stranger's life, she had to break the commandment against lying.