In the middle of the Dajing Dynasty, the imperial power was on the decline. The Zhenbei Houfu held military power and refused to join forces with the powerful prime minister Lin Song, so he was falsely accused of treason.
Overnight, all the members of the Hou family were executed. Only the young legitimate daughter Shen Qingci was taken away by his loyal servant. However, he was separated from his loyal servant during the escape and ended up living in the "Hanren Tower", a gangster killer organization.
At that time, heavy snow fell in the capital, covering the bloodstains in the Hou Mansion. Shen Qingci also learned the survival rule of "killing to stop killing" in the severe cold and despair.
Ten years later, Shen Qingci became the top killer in the "Hanren Tower", codenamed "Green Needle" - she was good at using needles and threads as weapons to kill people invisible.
In order to investigate the family injustice and avenge Lin Song, she gave up her identity as a killer and disguised herself as Jiangnan embroiderer "Su Wan". With the intelligence and support secretly provided by the organization, she returned to the capital, the land where her past was buried...
