A story of a woman who fights against the ruthless world of men to protect her only son. Hyun-jung, a used-to-be prostitute, is now the NO.2 of the gang which turns into a leading enterprise. Sang-hoon, who has been picked up by Hyun-jung, becomes the top killer in the gang. Hyun-jung is the reason why he bears all the dirty works in the underworld. Dae-sik, a fierce prosecutor, gets caught in a trap by Hyun-jung and is now forced to help to build up the gang's business, but seeks for the revenge. Meanwhile, the fatal weakness of Hyun-jung, the existence of her hidden son who she secretly gave birth in a prison, is revealed. The boy immediately becomes the target for every opponent including Sang-hoon. Blinded by jealousy, Sang-hoon plans to demolish the gang and negotiates with Dae-sik. Hyun-jung now starts the lonely fight to protect her son who doesn't even know his mother's existence.