Jackie (Nadine Marshall) is expecting her second child but the maths, doesn't quite add up. It's been months since she last slept with her husband Mark (Idris Elba), so she knows it can't be his. But she also knows she hasn't slept with anybody else. Prior to Jackie's discovery, she, Mark and son JJ (Kai Francis-Lewis) are a close-knit family living in London. Then comes Jackie's seemingly Immaculate Conception. Unable to explain her pregnancy she says nothing but knows it's only a matter of time before questions are asked and accusations will start to fly. As the child inside her starts to grow, so does everyone's concern for her state of mind, until it's not only the father of the child that is in question but Jackie's sanity as well.