19岁的女孩洁依（麦卡·梦露 Maika Monroe 饰）美丽迷人，她憧憬浪漫美好的青春恋情，却未曾想莫大的灾难突然降临。她和男孩休（杰克·威尔瑞 Jake Weary 饰）外出约会，期间休表现出恐慌的一面。在那个迷离的夜晚，燕好之后的洁依遭到休粗暴对待，继而得知休恐 慌的原因。原来一直有一个他人看不见的“人”跟随着休，TA可以变换任何人的容貌，并以杀死休为目标。摆脱TA的方法只有通过性将其转给其他人。自此之后，洁依无时无刻不出在恐慌之中，妹妹凯莉以及好友保罗、雅拉等人为其担忧，可是那看不见的追踪者随时随地出现。 　　TA是洁依无法摆脱的原罪，是投射在灵魂深处的恐怖阴影……For nineteen-year-old Jay, Autumn should be about school, boys and week-ends out at the lake. But after a seemingly innocent sexual encounter, she finds herself plagued by strange visions and the inescapable sense that someone, something, is following her. Faced with this burden, Jay and her friends must find a way to escape the horrors, that seem to be only a few steps behind.