The drama follows a fictional team of elite paramilitary officers from the Special Duties Unit of the Hong Kong police force. They specialise in counter-terrorism, hostage rescue, and crimes that are deemed too dangerous for regular police to handle. The unit works closely with the Organised Crime and Triad Bureau (OCTB) to crack down on terrorist groups.

• Joe Ma Tak-chung
• Linda Chung Ka-Yan
• Oscar Leung Lit-wai
• Lo Chung-him
• Mandy Wong
• Christine Kuo Yun-Hui
• Nancy Wu Ting-yan
• Benjamin Yuen Wai-ho