From the opening pages of Liz Tichenor’s memoir, “The Night Lake,” there is no forewarning, no preparation for death’s arrival. Ms. Tichenor’s five-week old son, Fritz, cries constantly. She takes him to a local urgent care doctor who pronounces the baby is “fine.” Only six hours later, Ms. Tichenor and her husband awake in the middle of the night to find their infant son dead.