A floating corpse at the Binhai City Pier has the marks of a serial killer from ten years ago engraved on its hands, and an old photo of a police officer who died in the line of duty is hidden in his arms. Jiang Chao, the head of the criminal investigation detachment, was ordered to investigate, but found that he had stepped into a carefully woven giant network.
A seemingly ordinary murder case is like a stone thrown into a quiet lake, causing ripples that have been buried for many years. Disappearing evidence, internal reports, blatant provocations from criminals... All clues show that the opponent is not only cruel, but also has "eyes" within the police force. As the investigation deepens, a huge criminal empire called "Undertide" gradually emerges. It is intertwined with drug dealing, cultural relic smuggling, and financial shady affairs, and its tentacles even extend to the core level of power.
Jiang Chao and his comrades, with the assistance of experienced veteran criminal police, top technical experts and colleagues with different intentions, launched a thrilling battle of wits and courage with a deeply hidden opponent. From the dark alleys of the seaside to the rain forests of the Golden Triangle, from the psychological games in the interrogation room to the life-and-death pursuit of international smuggling routes. Every time he gets closer to the truth, there are fatal traps and tragic sacrifices. The mastermind behind the scenes, the "Professor", controls everything like a ghost, and his last words of "more than one key" indicate that the crisis is far from over.
This is not only a battle between justice and evil, but also an ultimate test of legal beliefs and human nature. When the fate of two generations of policemen is intertwined with the truth that spans more than ten years, who can hold on to the final bottom line and light amid the turbulent undercurrents?
