Ellie and Joe Farrelly are a busy couple bringing up a teenage son while running a large building company. When they suddenly have twins, a stranger comes into their life at just the time when they need help the most.

After her 40th birthday party, Ellie and Joe celebrate on the kitchen table. Nine months later, they're the parents of twins. Ellie struggles to cope at home and Joe misses her presence in the office of the family construction firm. A chance encounter with a sympathetic stranger in the supermarket leads to a chilling and disturbing tale of manipulation and psychosis.