A strange murder case hides more secrets than you can imagine… In 1930s Shanghai, a detective finds himself embroiled in an intriguing murder case, with all clues pointing to his ex-girlfriend as the main suspect. As he investigates further, he uncovers hidden political agendas and widespread corruption lying behind the murder. Even while he grapples with his own emotions and the dark secrets he has discovered, a helping hand extends from an unexpected figure.

老警察李公安（戈治均 饰）和警校实习生张雷（李占河 饰）擒获诈骗犯于泰（傅彪 饰），押解其回陕西。一路上，年轻气盛的张雷看不惯李公安的做事没原则，很少给他好脸色看。在西行的客车上，天已渐晚，不料客车抛锚，司机折腾了半天没修好，于泰诡异地出起了歪点子，他唆使张雷贡献出新买的皮鞋做垫子，明知于泰捉弄自己，但为了一车人赶路，张雷只好忍痛割爱。车到县城，于泰被原先他骗过的一帮人围殴，混乱中，张雷身上的钱被小偷偷走，他一气之下病倒，幸得小旅店女老板相助。几天后，三人重新上路，于泰想趁机逃跑，不料误闯进采石场，为救于泰，李公安被炸飞的石块砸成重伤，于泰终于幡然醒悟......