Tells the story of Chen Si Xian, a young man who feels trapped in a relationship with his college sweetheart, Xiao Yu, who is constantly 'breaking up' with him. When she goes to Shanghai on a business trip, Si Xian decides to go out with an old flame but gets caught out. After suffering a tragedy, Si Xian goes on a journey to try and turn back time and change that regrettable night.

该剧讲述了都市青年人群的爱情烦恼与甜蜜茫然。某天夜里 ，女友出差，陈思贤的高中女神佳琪来到深圳，陈思贤应邀前去叙旧，不料他却喝得大醉，意识不清，与佳琪拥抱。此时小羽突然出现，原来小羽的航班被取消，归来却不见陈思贤在家，小羽只得跟着手机定位一路寻找过来。小羽提出分手，陈思贤却未挽留，反而大肆抱怨无法忍受小羽老爱提分手的毛病。小羽失望离去。当夜十一点，陈思贤辗转反侧，内心矛盾，无法入睡。决心向小羽先行解释，电话却始终不通。深夜十二点半，陈思贤在卫生间试图联系小羽。手机不慎落入马桶中，陈思贤急忙去捞，却被吸入了马桶之中。陈思贤消失不多时，马桶内的手机响起了一通警方的来电，事情发生了出人意料的转折