During the late Ming dynasty, the imperial court faces rampant corruption, compounded by an incompetent emperor. The Embroidered Uniform Guard (jinyiwei), composed of orphans trained from childhood in ruthless, covert combat, serves as a clandestine military unit for the Ming government. Among them is Qinglong, a commanding officer armed with a mechanical box housing 14 blades to aid him in his perilous missions.
The story escalates when Jia Jingzhong, a treacherous imperial eunuch close to the emperor, secretly conspires to overthrow the regime with the emperor's uncle, Prince Qing, an exiled figure from a failed rebellion. Jia manipulates Qinglong into recovering a safe box from imperial councillor Zhao Shenyang, claiming it holds evidence of the councillor's treasonous plans. However, Qinglong soon uncovers that the box actually contains the Imperial Seal, essential for legitimizing Prince Qing’s claim to power.
Betrayed by his comrades, particularly his brother-in-arms Xuanwu, who has allied himself with Jia, Qinglong finds himself on the run. Enter Tuo-Tuo, the fierce adoptive daughter of Prince Qing, who arrives just in time to assist him after hearing of his escape. As a fugitive still nursing his wounds, Qinglong turns to the Justice Security Service, a struggling private security company. There, he makes an enticing offer to the owner for safe passage out of the city, coincidentally hiding within the wedding carriage of the owner's daughter, Qiao Hua, who is on her way to marriage.
As jinyiwei operatives close in, Qinglong engages them in a fierce struggle, making it clear he is a former member of their ranks. The owner's newfound concern for his safety leads him to return Qinglong's fee and urge him to leave, but Qinglong is resolute in his intentions to uphold his duties. Taking Qiao Hua hostage, he sets off towards Yanmen Pass to gather intel on his adversaries, learning they plan to sell three provinces to support their cause.
Throughout his journey, Qinglong teams up with the Heaven's Eagles Gang, led by a formidable opponent known as the Judge of the Desert. Facing off in combat reveals them to be equally matched. Qinglong proposes a raid on the outpost at Yanmen Pass, engaging in a partnership with the gang for mutual gain.
As the narrative unfolds, Jia Jingzhong's betrayal leads to his downfall, murdered by Xuanwu, who aspires to serve under the ambitious prince. In a brutal raid, Qinglong and the gang triumph, yet Xuanwu escapes with the Imperial Seal. Meanwhile, Tuo-Tuo kidnaps Qiao Hua, demanding the seal for her release, leading to a tense stand-off.
Qinglong ultimately relinquishes the seal but insists on returning Qiao Hua to her fiancé first, showing his inner conflict. This sets off a series of confrontations, including an intense duel against Tuo-Tuo in an abandoned temple. The climax sees Qinglong and Tuo-Tuo locked in a fierce battle, culminating in the tragic demise of both characters.
In the aftermath, the rebellion under Prince Qing collapses, culminating in his suicide, while Qiao Hua inherits the Justice Security Service after her father's death. As she traverses the desert looking for remembrances of Qinglong, she holds onto a bell bracelet he gifted her, holding out hope for their paths to cross again when she sights a figure resembling him on the horizon.
