The two form a conspiracy to convince Oiwa and her sister, Sode, that their father had been murdered by known criminal Usaburo.
A year later, Iemon and Oiwa are married and living in Edo (the former name of Tokyo) with their infant son.
Tiring of his lack of status, as well as his marriage to Oiwa, Iemon begins to court Ume, daughter of the nobleman Ito.
He and Naosuke plan to poison Oiwa so that Iemon can marry Ume and become a wealthy nobleman.
The terrified Iemon attacks the spirit at his new home at night, accidentally killing Ume as well as both of her parents.
The ghost of Oiwa leads Sode to the home of Yomoschichi, who had survived the attempted murder.
The film ends with a vision of Oiwa, her appearance restored and holding her infant son, presumably in Heaven - her spirit now able to rest in peace with her revenge complete.
[1] From retrospective reviews, James Marriott commented on the film in the book The Definitive Guide to Horror Movies, proclaiming of the many adaptations of the play that "Nakagawa's is the classic."