Shanghai French Concession, 1940. His name is Shen Yan, a bartender at the Night Paris Bar. A neatly washed shirt gone pale, a mild, quiet smile. No one knows that a poisoned needle is hidden in his left-hand pocket watch, and even fewer know who he really is: the adopted son of the Hongmen Mountain Master and a secret agent for the Bureau of Investigation and Statistics. His parents died in a Japanese air raid. He has waited eight years. When a traitorous boss points him out in public as an anti-Japanese activist and an action squad from Unit 76 surrounds the bar, Shen Yan takes just five minutes to make the boss “die of a heart attack,” then fall to his knees and weep like a loyal servant. Then Captain Li Shijie says, “Come back to Unit 76 with me.” From that moment on, Shanghai has a new and most dangerous undercover agent. Humble as an ant in public, a merciless killer in private. His rule is simple: never let an insult go unanswered overnight, and always repay blood with blood.