狂风暴雨的夜晚，一身穿校服的女生死于天桥之上，不久之后，同班同学亦坠楼而死。这一切是巧合还是有人蓄意而为？一个条名为“六月的日记”的线索的出现将这几出命案联系到了一起。巡警秋子英（申恩庆 饰）首先发现了其中的蹊跷，可此时命案已被判为自杀。顶着巨大的压力，秋子英执着的继续 着自己的调查。 另一方面，与秋子英水火不容的同事金东旭（文政赫 饰）在法医处也得到了惊人的消息——凶手竟然通过日记预告了下一次的杀人行动。为了找到真相，秋子英和金东旭决定暂时放下曾经的恩怨，联手破案。而事实并没有表面上所显示的那么简单，随着调查的深入，更可怕的事情发生了。Two teenagers joining the same class in a high school die on the same day. The one to be top of the class is killed by a big knife on the street, the other - the second best of the class indeed - seems to be jumped from the top of the school building. Everybody believes that he first killed his classmate and than himself. But when the police finds small pill boxes into the stomachs of both kids confessing their murder two South Korean cops are torn into a new case of murder series. While they try to hunt down the serial killer, more pupils are getting killed...
