Kathryn and David are the ideal couple. But unseen by their envious or admiring friends, splinters are beginning to form. David suspects one of their two children is not his own and Kathryn struggles to iron out family confrontations to maintain the calm of their lives together. But slowly things start to slip from her control. David's mood swings become more irrational and violent. His drive to dominate and order the world he's created intensifies to the point of locking the playroom door and pocketing the key a move that signals the final route into the chaos that will disrupt their perfect world.