Isao, struggling with his conscience, confesses to Masako that he was the man Sayuri had the affair with, and was responsible for her death, although inadvertently.

To preserve the family's reputation and sheltered life, Masako begs her husband to keep his deed a secret.

When Isao eventually announces to turn himself in to the police, which he sees as the only way to find peace and maintain his personal honour, Masako poisons him with a soporific.

The Stranger Within a Woman was produced and distributed by Toho and received a roadshow theatrical release on January 25, 1966.

The film was released with English subtitles in the United States by Toho International in July 1967.