Until twelve years ago, geneticist Don Tillman had never had a second date. Then he developed The Wife Project and met Rosie, ‘the world’s most incompatible woman’. Now, having survived 4,380 days of marriage, Don’s life-contentment graph, recently at its highest point, is curving downwards. Rosie has just returned to work and is struggling with an obnoxious co-worker. Don, meanwhile, is in hot water after his latest lecture goes viral. But their real worry is their son, Hudson, who is having trouble at school: his teachers say he isn’t fitting in with the other kids. For Don, learning to be a good parent as well as a good partner will require the help of friends old and new. It will mean letting Hudson make his way in the world, and grappling with difficult truths about his own identity. It will also mean opening a cocktail bar.