六年前，两对大学生情侣来到乌木古镇旅游，在赋予了传说的断肠崖上，他们发下了爱的誓言，六年后，已经成为一名公务员的陈旭跟着旅行社故地重游，旅游的途中，他竟在断肠崖上神秘的失踪。几日后，好友魏端阳来到古镇寻找他失踪的真相，结果查访到陈旭失踪前和一个神秘的女子约会过。紧接着，古镇的海边惊现陈旭的尸体。围绕着陈旭死亡之谜，魏端阳展开了艰辛的调查，他循着陈旭生前的足迹，翻开了陈旭在大学时代的生活轨迹，无意中，他发现了六年前在陈旭的身上发生过一个可怕的秘密，然而不幸并未结束，又有知情人被杀害，凶手就像一个可怕的影子，(Six years ago, two couples of college students came to the ancient town of Wumu for travel. On the broken intestinal cliff of legend, they vowed to love forever. Six years later, Chen Xu, who has become a civil servant, came along with the travel agency. On the way, he disappeared at the broken intestinal cliff mysteriously. A few days later, his friend Wei Duanyang came here to find the truth of his disappearance. He found that Chen Xu dated a mysterious woman before he disappeared. Then, Chen Xu's dead body showed at the seaside of the ancient town. Wei Duanyang launched a hard investigation. He followed the footprints of Chen Xu and opened his college life. Inadvertently, he found that a terrible secret occurred to Chen Xu six years ago. Unfortunately, however, it was not the end. More insiders were killed. The murderer was like a terrible shadow,)