월하의 공동묘지(기생월향지묘)(1967) / Public Cemetery of Under the Moon ( Wolhaui Gongdongmyoji )

A former gisaeng who married into wealth is poisoned by degrees by the housemaid who wants her husband and her place in the household, and dies under a false charge of adultery with an infant son left behind. Her ghost rises from the grave to protect the boy, and the conspiracy against her unravels into murder, betrayal and a colonial-era police cell before it is done.

Why it's free: Free on the Korean Film Archive's own channel; the national archive holds the rights to the restorations it publishes.