When Dr. Meghan Weir first dons her scrubs and steps onto the floor of Children's Hospital Boston as a newly minted resident, her head is packed with medical-school-textbook learning. She knows the ins and outs of the human body, has memorized the correct way to perform hundreds of complicated procedures, and can recite the symptoms of any number of diseases by rote. But none of that has truly prepared her for what she is about to experience...