1945年,游学归来的刑侦专家程慈航,在码头遭遇险情,多方势力为争夺一只铁箱大开杀戒。这只铁箱里,存放着日军细菌武器的绝密档案。警察厅厅长莫采石将铁箱存放在了档案馆密室内,却在夜里档案被盗,案情从此扑朔迷离。程慈航获悉此案事关日军细菌武器,向“叔叔”莫采石请战,总署刑侦警察局局长霍然随即特聘程慈航为布衣侦探。程慈航上任后,很快找到蛛丝马迹,顺藤摸瓜接连捕获重大线索,然而他却处处受阻,总有人抢先一步将相关人员杀人灭口,幕后黑手究竟是谁?这个丢失的档案又究竟在哪里?程慈航究竟如何破解迷局,一切尽在答案尽在《昙花梦》里。In a desperate hunt to track down a top-secret metal box during World War II, China's best forensics experts are called to duty. The year is 1945, and an iron box containing the top-secret files detailing the Japanese biological weapons program go missing. Police director Mo Caishi (Gang Wu) assigns top police detective Cheng Cihang (Zhenyu Qiao) to help track down the missing files.