Following the success of part 1, "Sinister Beings 2" returns with a familiar cast. Two senior detectives Hua Tuan Sam (played by Tran Trien Bang) and Tham Vi Luc (played by Huynh Tri Hien) work together for the Organized Crime Investigation Team and the OCTB or Point O (Organized Crime and Triad Bureau). With their intelligence and sharp observation ability, they solve many cases.

Since relocation to Chek Lap Kok in 1998, passenger traffic at Hong Kong International Airport has increased threefold in twenty-five years. And Yeung Sheung-wai, who started out as a clerk, has been promoted to IAC Duty Manager. He is tasked with overseeing the operations of the airport. Sheung-wai also has a contingent of amicable partners, including his assistant-cum-admirer Fong Ho-yee, Lui Chi-shan – who handles airport passenger services – Chan Kit – who takes care of aviation security – and Lee Sing-cheung, who is responsible for apron services. They collaborate to assist in dealing with all kinds of incidents that take place at the airport. Sheung-wai keeps in touch with his ex-wife Cheung Yeuk-ling, Metro Harbour Airlines Airport Supervisor. Actually, they still think of each other after their divorce. The duo’s relationship is rekindled when airline captain Kwok Kai-kwong and flight attendant Ko Nga-man turn up.

Policewoman Yiu Chi-yue is a natural born Highly Sensitive Person. She brings chocolate, salty lemon water and a brain with an “on-off switch” with her whenever she investigates cases. Her senses are heightened when she drinks salty lemon water that arouses her keen awareness of clues at the crime scene. Through touching the dead body, gathering evidence and her senses, she empathizes with the victim and reconstructs the sequence of events. Since Chi-yue met restaurant boss Wong Mik-kei, the duo are no longer “spectators”. Perpetrators at large are killed one after another. Chi-yue covertly challenges some serial killer on several occasions, and their true identity is gradually uncovered. Chi-yue realizes the two of them have conflicting standpoints even though they are like-minded, causing her to face the conundrum of making life choices. In the meantime, Mik-hei astonishingly makes some decision for her.

Against the backdrop of neon lights in Hong Kong, there is a hidden dark side that nobody knows - the city is the hub of narcotics from all over the world. Rewind ten years and Narcotics Bureau has apprehended Man Wah, aka Drug Lord

The difficulty of buying a property in Hong Kong is the highest in the world. A supermarket manager who sold his property for cash during the 2008 financial crisis has chased property prices ever since to fulfill the dream purchasing a new flat for him and his wife.

Hui Chun-sum is an elite OCTB officer. He is fearless and competent. His boss thinks highly of him, and his colleagues really admire him. But his ultimate dream is to join SDU. Another elite OCTB officer Shum Wai-lik has a shrewd mind and extensive experience. Although the duo have different approaches, but they are like-minded and ideally complement each other. Police suffer heavy casualties as they are ambushed by thugs. To catch the culprit, Chun-sum forgets his dream and stays with OCTB. Moreover, Chun-sum and Wai-lik are faced with successive nasty cases that are tortuous, surreptitious, tricky and baffling. The duo use reverse thinking, psychological game theory and meticulous analysis to decipher the criminals’ thoughts and motives. No crook can escape the long arm of the law!