As an Asura assassin who has already retired from the pugilistic world, Qin Chen becomes personal bodyguard to beautiful CEO Shen Yuxi to repay a favor and investigate a family blood feud. Shen Yuxi becomes the target of multiple factions after developing the Source of Life, a new medicine capable of curing ALS and extending lifespan. Relying on extraordinary martial prowess and resourcefulness, Qin Chen successively foils the serial conspiracies of the local overlord Cheng family, the international consortium Sato, and top assassin organizations Mythology and Sakura Hall. Going from mutual disdain to deep love with Shen Yuxi, he also has to deal with emotional entanglements from female tycoon Ivanka and female assassin Jinghong.