After a series of suspicious deaths are disguised as accidents, detective Zhuang Lan leads a special investigation unit to uncover the truth behind the cases. As the team exposes hidden abuse, revenge-driven crimes, and impossible murder mysteries, they discover a secret organization known as “Lighthouse” manipulating events from the shadows.

明朝末年，在西域某地历代为朝廷出产黄金的大漠之中，老镖师带领镖队，告别了监管采金的官府安大人，押送黄金上路。镖队出发不久就遇见了第一拨前来劫镖的“马匪”，老镖师带领众镖师将其全歼，镖队自身也损失惨重。镖队再次上路，却被马三爷带领的第二波马匪击溃，在老镖师的拼死护卫下，儿子穆儿得以逃脱，镖队全军覆没。穆儿在马匪的追杀中，一条胳膊被砍掉。