公元前227年，卫国军队在凤凰山遭遇梁军伏击，血战之后惟有受重伤的卫国大将军（王力宏 饰）和装死的梁国士兵（成龙 饰）二人存活。将军有着统一诸国的宏图壮志，而小兵只想过自己的太平日子。小兵活捉大将，企图带着大将回到梁国，换良田五亩从此过上永无兵役的幸福生活。从凤凰山到梁国的路上，前有无数未知风险，后有卫国神秘小队追踪，小兵靠着美好信念的支撑以及自己的小聪明一次次化解危机，然而，在到达梁国之时小兵却出人意料的放大将返回卫国。小兵在江畔目送大将驾小舟渐渐远去，可是他并不知道在身后梁国的土地上，发生了一场天翻地覆的变化……Two armies clash in ancient war-torn China; none survive but a young general from a royal house and a farmer foot soldier who binds the fallen leader to take him home and claim a reward. Many stand in their way: an abandoned songstress, the noble's own murderous younger brother, desperate beggars, rough slavers, and the pair's own differing agendas. Through it all, a bond forms between the two, and what will happen at journey's end becomes anyone's guess.