A super special forces soldier is expelled from the army for taking down a notorious drug lord, fully aware of the severe repercussions. With the drug lord down, he averts the potential global catastrophe stemming from his empire. However, his mentor, the respected Old General, must uphold military discipline, and although reluctant, he could only follow the decision.

Before leaving the army, he visits the graves of his fallen comrades-in-arms, where he unexpectedly encounters Su Qingyue, the military advisor of their elite team. Informing her of his erased records, he finds solace in her disappointment mixed with relief. Inquisitive about his future plans, Su Qingyue becomes a pillar of support.

Yearning for the warmth of family, he confides in her, expressing his desire to return home and reunite with his beloved little sister. Embracing his decision, she vows to handle any interference from their former team, and their conversation culminates in a passionate kiss, an intimate moment marking the beginning of a new chapter in their lives.

Six years of absence melt away as he steps into his hometown, only to be greeted by an unrecognizable cityscape, a stark contrast to his cherished memories. As he embarks on his journey to reunite with his last remaining family, fate intervenes when he overhears a woman's anguished cry for help. Despite his yearning to head straight home, his instincts compel him to intervene, drawing him into a precarious situation.

Moving toward the source of distress, he witnesses a group of hooligans menacing a young woman. Though she brandishes a switchblade and confronts the thugs with unwavering bravery, it becomes apparent that she struggles to defend herself. Unable to stand idly by, he emerges from the shadows, unaware of the chain of events his selfless act has set in motion. Little does he know that his past is about to catch up with him, forcing him to confront the unforeseen consequences of his actions in a thrilling and unpredictable turn of events.

C121 Promise Me One Thing