一九九五年，广东发生一起大型武装劫钞案，一辆银行运钞车被五名持枪匪徒抢劫，损失高达一千五百万，三名押钞员更在事件中丧生。事件震惊全国，公安局马上成立专案组，以王守月（林家栋 饰）和何蓝（张颂文 饰）为首的刑警迅速搜证，成功掌握五名抢匪去向并逐一拘捕。叫人意外的是，抢匪供出案件背后的真正策划者，竟是一家建筑公司的老板陈信文（大鹏 饰）及其堂弟陈欣年（孙阳 饰）。 陈信文和陈欣年功败垂成，踏上逃亡之路，从此人间蒸发。时间一晃二十一年，当年的案件早已淡出大众的视野，王守月也从公安局退休。然而，一条寻常不过的视频上出现的一个模糊身影，却让他重燃破案的希望。王守月只身前往边境城市，寻找视频中的“陌生人”。最后的正邪对决，在二十一年后正式展开。In 1995, a large-scale armed banknote robbery occurred in Guangdong, where a bank cash truck was robbed by five armed bandits, resulting in losses of up to 15 million yuan. Three banknote chargers also died in the incident. The incident shocked the whole country, and the Public Security Bureau immediately established a special task force. Criminal police led by Wang Shouyue and He Lan quickly searched for evidence, successfully grasping the whereabouts of five robbers and arresting them one by one. Surprisingly, the real mastermind behind the robber's confession was Chen Xinwen, the owner of a construction company, and his cousin Chen Xinnian. Chen Xinwen and Chen Xinnian were on the verge of success and failure, embarking on the path of escape, and from then on, the world evaporated. Time flies for 21 years, and the case of that year has already faded out of the public's view. Wang Shouyue also retired from the public security bureau. However, the blurry figure appearing on an ordinary video reignited his hope of solving the case. Wang Shouyue went alone to the border city to search for the \"stranger\" in the video. The final battle between good and evil officially began 21 years later.