Seeking a fresh start for their marriage, Briton Anna and her Australian husband Jake move to Melbourne with their two small children. With Anna resuming her career, they hire a young live-in nanny to help - but local girl Becky is anything but the innocent stranger she pretends to be. 

Lulled into a false sense of security, Anna recommits to Jake. She continues to confide in Becky, unaware that Becky is under Jake's spell and plotting together with him against her. Later, a shocking turn of events leads Anna to discover the truth of what is going on, and she decides she is not going to be a victim any more.