When 10-year old Olivia's Mom goes on a business trip for the weekend, she leaves Olivia home alone with her 17-year-old brother Miles in charge. The first night, Olivia falls asleep on the couch, and wakes up, not realizing how late it is. She walks her dog Charlie without Miles knowing, and witnesses a young woman being kidnapped on the empty New York City streets. Olivia runs home and tells Miles, but he doesn't believe her. The next morning, she explains what happened to local cops, and they don't believe her either! Only a cynical female detective named Dottie (played by Academy Award winner Susan Sarandon) listens to Olivia, but she too is skeptical. Undaunted, Olivia bravely launches her own investigation, putting herself into perilous situations. Her can-do spirit ignites one extraordinary adventure after another. Can she outwit the bad guys and convince her brother and Dottie of the truth in time to save the day?
玛丽(艾丽·范宁 Elle Fanning 饰)是一个从小就沉迷于怪力乱神的鬼怪神话之中的鬼马少女,她继承了父母的先进思想,个性独立自强又桀骜不驯。为了让女儿接受更好的教育,玛丽的父亲将她送往了自己的友人威廉(德里克·里德尔 Derek Riddell 饰)家中,在那里,玛丽遇见了浑身充满了忧郁气质的年青诗人雪莱(道格拉斯·布斯 Douglas Booth 饰)。