British woman Anna and her husband, Jake, relocate to his native Australia with their two small children. Haunted by mysterious events that occurred in London, Anna resumes her career and welcomes a young nanny into the house. Nanny Becky seems a perfect fit for the kids, but Anna and Jake's arguments soon shatter the peace.

Lulled into a false sense of security, Anna recommits to Jake. Meanwhile, Jake and Becky continue their affair while secretly plotting to gain custody of the children. Becky is clearly under Jake's spell, while Jake loves that she's sexually adventurous, unlike Anna.

Becky is conflicted when Anna tells her that Jake is physically abusive, showing her a bruise on her shoulder and claiming that Jake hit her. When Jake lures Becky back into his orbit, Anna realises she has to take drastic measures.

Becky helps Anna set up an apartment where she is safe from Jake, and on the day Anna is due to move out and take the kids, she asks Becky to stay at home with Jake, and events take an unexpected turn.