The Halleys are a close, successful, loving family. But when identical twins, Nicholas and Michael, fall for the same girl, relationships become increasingly complex. As a GP, their mother Roberta, came into possession of information which could spell unhappiness for both her sons, but her strict code of ethics limits what she can share. She watches with growing dread as they both embark on family life, making decisions which compromise the stability of their marriages and the welfare of their children. But as time goes on the moral values of both young couples are challenged by an unplanned pregnancy, infertility, and a surrogate arrangement, revealing darker secrets and hidden dangers. Then, just as Roberta begins to relax her vigilance, the greatest threat of all comes from a completely unexpected source.