Donor Unknown follows the story of JoEllen Marsh, 20, as she goes  in search of the sperm donor father she only knows as Donor 150. What impact will meeting this stranger – Donor 150 - have on their children? What kinds of relationship can the children build with their biological father? How will letting Donor 150 into their lives affect their relationships as a family? And how will meeting his biological children change Jeffrey’s life?