The film presents a captivating fictional origin story surrounding the well-known poem Full River Red (滿江紅), which is attributed to the legendary General Yue Fei. Set in the year 1146, four years after the death of Yue Fei, the narrative begins with a shocking event—the murder of a Jin envoy in the residence of the Song Dynasty's Prime Minister, Qin Hui. In a sweeping act of brutality, the guards assigned to protect the envoy are captured and executed immediately. Among them, Zhang Da, portrayed by a determined actor, is on the verge of execution but claims to possess valuable information about an item left at the crime scene. He is subsequently taken before Qin Hui, played by a formidable actor, who gives Zhang two hours to track down a crucial missing letter that could paint him as a traitor.
Complications quickly arise when Sun Jun, the deputy commander and Zhang's uncle, is reluctantly assigned to assist him. Their relationship is strained, as Sun Jun, portrayed by an intense actor, harbors disdain for Zhang. Tensions escalate as Qin Hui orders the execution of both men, regardless of whether they successfully locate the letter.
As Zhang and Sun pursue various leads, their struggle intensifies, particularly as an uncontrolled Sun Jun dispatches several potential witnesses, including a Jin interpreter. Just as they face the threat of execution by Qin Hui, Zhang's quick thinking leads to a temporary reprieve; he suggests they can cover up the envoy's presence, allowing them one last chance to search for more leads or else bear full responsibility for the chaos.
In their quest for answers, Zhang surmises that the culprit must have connections within the kitchen and reaches out to his friend Liu Xi. However, Liu's assassination attempts go awry and he is captured. Under pressure, He Li, Qin Hui's second-in-command, suspects Zhang, Sun, and another official Wu Yichun. They are forced to betray their friend Liu, proving their loyalty through an act of violence. After being released, Wu senses that the blank letter found is a ruse, and together with Zhang and Sun, they seek the help of Zither, a courtesan, for interpreting a letter written in Jin language.
Tragedy looms over Zither, who reveals the risks involved in interpreting the letter, as doing so would threaten her life. Her plight becomes entangled with Zhang's growing awareness that all of them might be sacrificed once she reveals the letter's contents. Fearful of their fate, Zhang persuades Wu to arm Zither with a dagger, hoping she can take Qin Hui hostage if necessary. In a tense confrontation, Zither's attempt to assassinate Qin fails, leading to devastating consequences as Wu is executed for the implications of the plot.
The tension reaches a climax when He Li accuses Zhang and holds him and Sun captive, while Zither devises a clever distraction to eliminate He Li, but tragically pays the ultimate price in the process. Now awaiting execution, Zhang unveils a method to trap Qin by transcribing the letter's incriminating message on the wall of their cell. As Qin arrives to read it, the atmosphere thickens with treachery and imminent violence. Just as Zhang attempts to eliminate the Prime Minister, a twist of fate leads Sun Jun to intervene, resulting in a heart-wrenching confrontation between them.
In a shocking turn, Prime Minister Qin grants Sun a lavish reward of 1000 taels of silver and the role of director of his office. However, the darkness of their past looms large as Sun, knowing Qin's true nature, questions him about General Yue Fei's last words, demanding his final poem be recited before the soldiers. As Qin performs this act, he reveals his own cowardice, ultimately leading to his self-inflicted demise, which reveals a twist of fate as a body double takes his place.
The film culminates in the heart-wrenching realization that Sun Jun allows Qin Hui to live, believing that a life of shame and public disdain would be a far worse fate than death. With an escape planned, Sun leaves the chaotic scene with two loyal subordinates, leaving the audience pondering the intricate web of loyalty, betrayal, and the haunting legacy of Yue Fei's words. Through meticulous storytelling and compelling performances, this narrative intricately portrays the depths of human nature amidst historical turmoil.
