As in her previous book, “Grace,” Delfina Bertolon shows complex relationships in the family. Big and Little, two sisters. The youngest dreams of loneliness, but her mother also told her: “If you have a sister, then you can’t escape her.” Little is burdened by communicating with Big, but when she is gone, she realizes that she knew almost nothing about her sister. Little by little, secrets are revealed to her that she would prefer not to know about. But, alas, “if there is a sister, then there is no escape from her.”