The film is about Marlo, a mother of three including a newborn, who is gifted a night nanny by her brother. Hesitant to the extravagance at first, Marlo comes to form a unique bond with the thoughtful, surprising, and sometimes challenging young nanny named Tully.

Will and Eden were once a loving couple. After a tragedy took their son, Eden disappeared. Two years later, out of the blue, she returns with a new husband... and as a different person, eerily changed and eager to reunite with her ex and those she left behind. Over the course of a dinner party in the house that was once his, the haunted Will is gripped by mounting evidence that Eden and her new friends have a mysterious and terrifying agenda. But can we trust Will's hold on reality? Or will he...