The forensic department teams up with the police to solve a series of challenging cases.
Tim Sir, a brilliant forensic expert, uses his deep knowledge and unique methods to uncover vital evidence and crack seemingly unsolvable crimes. He works closely with his trusted friend Sam, an exceptional forensic doctor who is preparing to marry his girlfriend, Lam Ding Ding. Their circle expands with the return of Ivan from England, who gains Tim Sir's respect after defusing a bomb during a tense emergency.
Meanwhile, Senior Inspector Ma Kwok Ying of the anti-drug unit leads a high-stakes mission to take down a dangerous drug lord — but the operation ends in a devastating explosion, triggering far-reaching consequences.
