Xiao Yi, the Hell King of the Northern Prison who shakes the world, conceals his identity and works as a humble security guard to protect his cold and aloof fiancée, CEO Shen Chumo. Shen Chumo's company develops a breakthrough drug, Life No. 1, which attracts successive hunts from the four major families, underworld forces, and escaped violent criminals. Playing a pig to eat a tiger, Xiao Yi reverses the situation layer by layer amidst corporate warfare, the underworld, and conspiracies as his identity is gradually unveiled. Shen Chumo also shifts from disdain to deep affection, and the two ultimately become a devoted couple after experiencing life and death together.