Tom Alden is a 50-something former fisherman who lived life as "the indestructible American male" in his surgeon's words. That is, until he was diagnosed with colon cancer. Coming to terms with his own mortality is tricky psychological terrain for this confident and supremely self-reliant man. His surgeon, David Berger, is as good as they come but knows Tom's chances of survival will be affected by how far the cancer has spread.Amy Rezak is one of only a handful of female trauma surgeons at major hospitals. Gunshot wounds, car crashes, patients who are sometimes hopelessly maimed or injured, are typical in Amy's line of work. An adrenaline junkie with a dark sense of humor, Amy has what the military refers to as "command presence" in her OR. Her personal life is another matter. Like many other residents, she would rather go home to a relationship, if she could make one work, than an empty apartment.Caitlyn MacPhee is a 4-year-old little girl who is choppered to Children's Hospital Boston in the middle of the night with bleeding in the brain. Her family alternates between moments of frustration and gratitude toward hospital staff as they try to cope with a situation that most parents hope to never experience.