In a medieval Japan devastated by war, an older woman and her daughter-in-law survive by murdering samurai lost in the reeds, so that they can sell their armour for food. However, their partnership is threatened by the return of a deserter neighbour and the arrival of a samurai wearing a strange mask. Heavy with eroticism and violence, Onibaba is a mystical, gruesome story that reflects on the horrors of war and the morally destructive consequences of actions committed in the name of survival.