Perfect Marriage

Ben and Daisy Bechdel, secretly brother and sister, live as a successful married couple. He is an orthopaedic surgeon, she is a pathologist. They have no children although she did have a stillborn daughter in France after which she had a mental breakdown, leading to a break from work. But maybe the baby survived... What if it did? Why was she lied to by her husband and sister about it? Becoming obsessed with this possibility, Daisy hires a PI...