Set in the 1930s, a Japanese death cult known as the Temple of Hades kidnaps Chinese children and brutally trains them to become lethal assassins serving their expansionist agenda. Vajra, one of the abducted children, endures grueling torment and transforms into a formidable warrior through relentless training. His masterful combat skills earn him the recognition and name of K-29, an elite assassin. However, internal conflict gnaws at Vajra, who yearns for freedom and justice rather than subjugation. This inner strife leads him to a pivotal decision to flee from the Temple, setting him on a path of vengeance.

After years in hiding and honing his combat prowess further, Vajra resurfaces, driven by a mission to dismantle the Temple of Hades and liberate others from its monstrous clutches. He infiltrates their base, battling adversaries steeped in dark arts and martial expertise. As he advances, he encounters past comrades warped by years of indoctrination and violence. With each confrontation, his resolve to dismantle the cult intensifies, confronting the deepest shadows of his past and the darkest corners of human cruelty.