单身白领方卉独居在家时，常常觉得不安，似乎有一双看不见的眼睛在窥视她的日常，伴随着身边种种让人不适的遭遇，恐怖的真相逐渐逼近……

單身貌美的方卉（白百何 飾），獨自在大城市打拼，過著兩點一線的生活。一天夜裡，她突然聽見門外有人暴力拉拽門把手試圖闖入。雖然沒有看清門外是誰，但通過保安小吳得知，自己樓層的監控壞了。這讓方卉平靜的獨居生活突然籠罩在驚恐不安的陰影之中。

當夜晚再次降臨，熟睡中的方卉隱約察覺有人進入了她的房間，但她醒來後卻沒有發現任何跡象。漸漸，她的精神狀態也開始變得越來越差。身邊反復出現的幾個男人，房屋中介高齊、保安小吳、公司領導李總、寵物醫生鄭飛，他們似乎都有自己不可告人的目的。隨著好閨蜜喬小曼的離奇失蹤，獨居，幾乎成為了方卉的夢魘……

A woman living alone starts to feel uneasy when she discovers traces of a stranger having been in her home. Single and beautiful Fang Hui works alone in the big city. One night, she suddenly hears someone outside the door trying to break in, violently pulling the door. A security guard notices that the floors monitor are broken. This made Fang Hui's peaceful life of living alone suddenly shrouded in the shadow of anxiety. When the night came again, sleeping Fang Hui vaguely notices that someone had entered her room... but she didn't find any signs when she wakes up.