Three years ago, national security agent Guo Jingan was betrayed during an overseas mission and his partner died. He was forced to remain anonymous and lurk in the city with a "turtle" style - low-key, patient, and unrevealing. He opened a small teahouse. On the surface, he was a Buddhist owner who was independent of the world, but in fact, he was secretly tracking down the mole who betrayed information back then. Until one day, a mysterious man who calls himself "Mockingbird" suddenly appears in front of him, claiming to know part of the truth of the year, on condition that he help him complete a secret task: stealing a top-secret document from Shen Wanshan, chairman of the city's largest real estate group "Shengshi Huating".
Guo Jingan discovered that Lin Yaodong, the first secretary next to Shen Wanshan, was the bully male partner who seemed honest and honest, but was actually ruthless. On the surface, this person is gentle and elegant, but in fact he controls many unknown gray transactions of Shen Wanshan, and even has inextricable connections with foreign forces. What shocked Guo Jingan even more was that Lin Yaodong held a secret that could subvert the political and business landscape - and this secret was the reason why he betrayed Guo Jingan.
When Guo Jingan decided to go deep into the tiger's den, an unexpected thing happened: Lin Yaodong took the initiative to find him, claiming to "share a secret about your past." Is this secret a trap or an opportunity? In the confusing game of wits and counterattack, Guo Jingan must use the unique tenacity and patience of the turtle family to uncover the truth step by step and dance a perfect waltz on the tip of the knife.
