Child psychologist Laverne Antrobus sets out to test the science behind a father's influence on children, starting with a new dad experiencing Couvade Syndrome, a condition with symptoms resembling sympathetic pregnancy. A blood test raises the possibility that hormonal shifts in expectant fathers prepare them for a nurturing role. In the lab of a researcher who studies fatherhood, Antrobus watches fathers and toddlers at rough-and-tumble play, the kind of physical roughhousing that turns out to teach children about limits and aggression rather than just burn off energy. The film's later sections turn to father-daughter relationships, looking at research linking the quality of that bond to the kind of partner a daughter later chooses, and to studies connecting absent fathers with earlier puberty and faster physical aging in girls. Antrobus runs an experiment with a group of married women to put these claims to a practical test. The film moves from body chemistry to child's play to adult relationships, treating fatherhood as a measurable biological force rather than a cultural assumption.