Bomb disposal expert Yeung Yat Sing, Ivan, returns from England to visit relatives and happens to come across a grenade case by accident. Ivan's skills are highly appreciated by Senior Chemist Ko Yin Bok, Timothy, and he is invited to join the Forensic Division. Ivan soon becomes the division's rising star. Ivan gets back in touch with his long-lost best friend Koo Chak Sam, Sam. Sam serves as a forensic writer and he is going to get married soon. During a case, Sam's fiancée Lam Ding Ding and Timothy's police girlfriend Leung Siu Yau are caught in an explosion meant to kill two drug dealers. Ding Ding dies of her injuries, while Siu Yau loses movement in her right hand and goes half-deaf. Yau's duties are passed to Ma Kwok Ying, Bell, from the Narcotics Bureau. Both Sam and Ivan find Bell extremely charming with her smart and unfathomable characteristics in case handling. Then Ivan fell in love with Bell and the two become a couple. Integrating laboratory techniques, logical reasoning, and forensic knowledge, the trio strive to fight against crimes tremendously. As they get to know each other more and more, the entangled triangle of love also starts to hinder their working relationships.