When Sara leaves her high-flying London life to move to Dublin, her only concern is her nine-year-old daughter, Lexie. For Lexie's sake she tries to get to know other mothers at the school gates, but they appear uninterested - particularly their leader, the beautiful and charismatic Vanessa, whose daughter rules the playground.

After a simple misunderstanding between Vanessa and Sara, none of the other kids at school want anything to do with Lexie. Desperate to mend fences, Sara offers to look after Vanessa's daughter one afternoon. But when the playdate ends in catastrophe, Vanessa is convinced that what happened wasn't an accident.

With allegations flying in all directions, Sara is forced to ask herself what she has unleashed? And how far a mother will go to protect her daughter?