Against a backdrop of the Qing era, due to his father Sung On working as a prison guard, smart and clever Sung Sai-kit has witnessed all kinds of unjust things as he has been wandering around within the prison walls since his childhood, causing him not to believe there is justice in the legal field. After reaching adulthood, Sai-kit also does not want to become an imperial official even though he is well educated. He just covertly helps a fellow student called Ho Sau-shun pass his exam. And Sai-kit and his brother Sung Ah-kau follow a nomadic lifestyle. However, Sai-kit is then embroiled in the Murderous Spider Demoness Case. To find the perpetrator, he shows off his finesse as Pleader. During the process, he also meets brothel bouncer Ling Lung, who is a proficient combat fighter. The case is concluded, and Sai-kit and Ling Lung get married. He also properly goes down the road to working as a Pleader. Moreover, he has to deal with successive complicated big cases.
A brutal murder case causes twin sisters to be reunite again. Their life trajectories, which are like parallel lines, get intertwined. They exist in different realms when they meet again. Due to investigation into an explosion case, Hong Kong police officer Yuen Sing-kit reaches Singapore. His girlfriend Leung Hei, an insurance claims investigator, is missing. While cracking down on people smugglers, Singapore STAR Wei Xiao Chen discovers her younger sister Leung Hei’s dead body. Wei Xiao Chen’s sister’s tragic death causes her to recall her childhood memories. To catch the perpetrator and find the truth, Wei Xiao Chen goes to Hong Kong. She disguises herself as Leung Hei and investigates people around Leung Hei. When the conundrum is about to be deciphered, she finds out Leung Hei’s death had implications for other crimes. Wei Xiao Chen gets further from the truth as investigation progresses. The darkness behind the crimes is bottomless.