At San Antonio Memorial, those who work the 7pm – 7am shift are a special breed. Welcome to the night shift, where every day is a fight between the heroic efforts of saving lives and the hard truths of running a hospital. After a grueling tour of duty in Afghanistan, adrenaline junkie TC Callahan became accustomed to combat, but he could have never guessed that his toughest battles would be fought right here at home. TC and his irreverent team of late night docs know how…