This is an unusual Shaw Brothers period kung fu thriller in that the hero is a member of The Ching Dynasty, almost without exception the villains in these films. After displaying his martial prowess by defeating challengers from Mongolia (Lee Hoi-sang) and Shaolin Temple (Gordon Lau Kar-fai), Wai Fung (David Chiang Da-wei) is ordered by The Emperor (Frankie Wai Wang) to undertake a special mission. He is to spy on the affluent Tien family, which is suspected of having ties with Ming revolutionaries. Fung gains access to the Tien home by getting hired on as a teacher for Gi-gi (Wong Hang-sau), a bratty young girl who has driven away more than her share of instructors. After the expected period of adversity, Gi-gi becomes fond of Fung, and when his identity is compromised, she claims to be his lover. Against his better judgment, the Tien patriarch (Lau Kar-wing) decides to spare the Manchurian's life, on the condition that he never leave the estate. The pair are married, but unless Fung can gather the required intelligence information and report back within a year, his family will be executed. Gi-gi decides to stand by her husband's side and the pair attempt to escape, but this means they will have to defeat the Tien family's most powerful fighters (including Norman Tsui Siu-keung, Wilson Tong Wai-shing, and John Chang Wu-lang).

While exhilarating, the martial arts are not as consistently spectacular as those commonly found in director Lau Kar-leung's films from this period. However, like the best films in the genre, kung fu is not the only point of interest here. The screenplay offers up a number of interesting twists, as well as some thoughtful ruminations on loyalty. There is the obligatory third act episode in which the hero masters a special skill in order to defeat the powerful enemy (a beautifully realized sequence in which Fung creates the "Mantis" fighting style by observing a real praying mantis), but even the final outcome of this is not exactly as one would expect, incorporating one last, ironic revelation into a refreshingly offbeat scenario. Lily Li Li-li and Ha Ping also appear.