正值花季的美丽女孩凯西（Odette Yustman 欧黛尤斯曼 饰）近来饱受困扰，她经常能看到一名面容阴森如幽灵般的男孩充满憎恨地望着她。凯西求助好友和医生，但都不见效果，不过却从眼科医生那里得知自己可能拥有双胞胎兄弟/姐妹的消息。这一点随后在父亲那里得到证实，凯西通过翻检母亲的遗物找到线索，并拜访了身在养老院的索菲（Jane Alexander 饰）——一个二战时期大屠杀的幸存者。索菲向其讲述了纳粹对集中营中的双胞胎所做的残酷试验。而这一切都与凯西的遭遇有着千丝万缕的关系。 　　随着调查的深入，凯西离事实的真相越来越近……While babysitting a boy and his baby brother, Casey Beldon has a dreadful nightmare involving a weird dog and an evil child, and she tells her best friend Romy over the phone. Casey is haunted by this boy, and when she goes to the ophthalmologist, he asks if she has a twin brother or sister. She asks her father and discovers that her mother lost a son that died in the womb. Casey suspects that she is haunted by the spirit of her brother. She finds a letter addressed to a woman called Sofi Kozma and a creepy picture at home that belonged to her mother. She goes with Romy to a retirement home to meet Sofi, a survivor of the experiments during the Holocaust. But Sofi tells Casey that she had never met her mother and later calls Casey to tell her she is in great danger.