Linda has a seemingly perfect union with her rugged and handsome husband Mark and an adorable daughter. But if an babysitter who has become dementia injures Chloe, Linda wants to ensure that her child is never hurt . Initially, Heather, the roommate that is newest, seems for this family that is practically perfect. But Heather is really a schemer who joys in the resulting chaos, also exploits the cracks in Linda's relationship and Mark. Heather's intentions go far beyond the mischievous Since Linda learns, to her horror.