Hong Kong crime movie from 1978

Hong Kong movie

On a rainy night, a robbery took place in a villa and some invaluable jewels were taken. One of the robbers was shot dead, the other wounded. The wounded robber dropped the leather case containing the jewels and it fell on to a rock beneath a suspension bridge. Chiang Wen Hua was a schoolteacher who was separated from her husband. On a Sunday afternoon, Chiang and her daughter Hsiao Ching went picknicking near the suspension bridge. Hsien Ching's paper windmill was carried away by the wind, and, in looking for it, Hsiao Ching found the leather case containing the jewels...