David Chiang plays Wai Fung, a Qing scholar who is sent to infiltrate the Tien family, a well known base for Manchu support. He quickly makes himself part of the family and takes over the tutelage of their youngest daughter Tien Gi Gi (Cecilia Wong). His family having been threatened if he does not report information, Wai constantly sneaks around the compound looking for secrets, which leads to a few close encounters. However, he can find nothing and his father and mother are demoted, jailed and finally threatened with death. Wai decides he has no choice but to leave, but by this time the Tien's have figured out his secret. Tragic consequences follow as Wai tries to break out of the compound and return to his family.
Shaolin Mantis had a great concept, but in the end failed to meet with my high expectations of a Liu Chia-Liang directed film. David Chiang has never been in my list of favorite martial arts actors, but he is usually surrounded by excellent fighters who make up for his lack of skills. He is rather slow and seems to be following strict patterns, while the other fighters react to him. Wilson Tong, John Cheung and especially Lau Kar-Wing seem blindingly fast and skilled compared to Chiang. David is an excellent actor, but he is not particularly suited to kung fu-centric films. Another slight disappointment was the fact that the mantis style never really makes an appearance until the final 20 minutes or so of the film. There was good use of mantis weapons (i.e. 3-section staff, twin daggers and staff), but it was all too brief to be satisfying.
The plot had very interesting twists, with David Chiang portraying the seemingly sympathetic role of the Qing scholar, and the Tien family (Kar-Wing, Cheung, Chu and Tong) playing Manchu sympathizers and antagonists. A twist in the finale seems to bring everything back to the normal Shaw Brothers political bent. The acting overall is excellent, with nods to Chiang and Cecilia Wong for their many humorous scenes. Wong is quite funny as a jubilent teen more interested in training in kung fu and playing tricks than learning reading and writing from Cheung.
Shaolin Mantis could have been a legendary film with a more accomplished martial arts practitioner and more focus on the development of the mantis style and good training sequences. Instead of seeing Gordon Liu in a cameo appearance as a Shaolin monk who gets soundly beaten, I would have preferred to see him in the lead role, fighting in one of the most interesting and cinema-friendly styles out there.

6/10