They were once brothers fighting side by side, but also rivals spanning two decades.

The story is set in the late 1990s, a time of shifting international dynamics and escalating cross-strait tensions, which spark a major case. Beneath the surface lies an intense intelligence battle between foreign forces and domestic operatives. When he first joined the National Security Bureau, his senior was already a rising star. Despite their vastly different personalities, the two worked together tirelessly to counter relentless espionage efforts from foreign powers. Through countless clashes, they successfully dismantled enemy operations. Years later, as a similar case resurfaces, he is shocked to discover intricate ties between the investigation and his former mentor. Spanning two decades, this is not just a struggle for national security but also a story of transformation and confrontation between two brothers-in-arms.