دهه ۱۹۳۰، کُره. در دورهٔ اشغال ژاپن، مردی شیاد برای اغوای زن ثروتمند ژاپنی و راضی کردن او به ازدواجش با وی، دختری را بعنوان خدمتکار برای آن زن، استخدام میکند. وظیفه این خدمتکار قلابی راضی کردن زن به ازدواج با آن مرد است. با این حال رابطه ای عاشقانه بین خدمتکار و زن ثروتمند شکل می گیرد.
زن ثروتمند که به همراه عموی مرموز و خشن خود زندگی میکند در غیاب عمو موفق به فرار با آن مرد میشوند. با اینحال با اتمام پولشان و برملا شدن نقشه مرد شیاد و دخترک خدمتکار، زن دست به خودکشی میزند. دخترک، او را از مرگ نجات میدهد و به گناه خود اعتراف میکند. او به زن کمک میکند مرد را مسموم کنند و تمام کتابهای سادیستیک عمو را نیز از بین میبرند و طی نقشهای، مرد شیاد را به دام عموی زن (که بیمار روانی و دارای انحرافات جنسی است) میاندازند. عمو، مرد را شکنجه میکند تا او داستان رابطه جنسی شب ازدواجش با برادرزادهاش را برای او تعریف کند. شکنجه از حد بیرون میشود و مرد با سیگار آغشته به جیوه خودش و عمو را مسموم میکند و هر دو با هم میمیرند. زن و خدمتکار نیز با لباس و هویت مجعول به چین میگریزند و رابطه خود را ادامه میدهند.
In Japanese-occupied Korea, a con man operating under the sobriquet of “Count Fujiwara” plans to seduce a Japanese heiress named Lady Hideko, then marry her and commit her to an asylum in order to steal her inheritance. He hires a pickpocket named Sook-hee to become Hideko’s maid and encourage Hideko to marry him.
Hideko lives with her Uncle Kouzuki, a Korean man who helped the Japanese take over his country in exchange for a gold mine. Kouzuki then uses this wealth to feed his obsession with rare books, selling forgeries to further accumulate money and books. Sook-hee’s main job is to help Hideko prepare to read for Kouzuki’s guests. Returning frustrated from a reading, Hideko demands Sook-hee sleep next to her. The two end up making love, under the pretext of preparing Hideko for her married life with the Count. Sook-hee begins expressing reluctance about the plan, but when Hideko herself suggests she loves someone other than the Count, Sook-hee insists on the marriage. Hideko slaps her and violently throws her from the room.
When Kouzuki leaves on business for a week, Hideko and Fujiwara elope. After cashing out Hideko’s inheritance, it is revealed that Hideko’s naïveté was part of the con. She and Fujiwara double-crossed Sook-hee and convinced the asylum that she is the “Countess” to have her committed in Hideko’s stead.
A series of flashbacks show that Hideko’s “reading practice” was in fact Kouzuki teaching her to erotically read sadistic pornography since she was five years old. The flashbacks show a regime of psychological and physical abuse that eventually degrades Hideko’s aunt’s sanity. Hideko’s aunt is eventually found hanged from a tree in the yard, and Hideko takes over as the reader for the pornography auctions. When Hideko questions the description of a hanging in a book she has to read, Kouzuki tells her that he murdered her aunt using torture devices in the basement after she attempted to run away.
In the more recent past, the Count realizes seducing Hideko would be impossible and instead includes her in the plan to elope and then split her inheritance. When Hideko expresses her fear of her uncle, the Count promises her a vial of fast-acting poison as a wedding present, so that she can never be taken to the basement. Hideko demands the Count find her a girl to hire as a maid, to commit to an asylum in Hideko’s place.
While being instructed by the Count, who takes advantage of Sook-hee’s illiteracy, Hideko unexpectedly falls in love with her. Hideko tries to confess her love, but when Sook-hee insists the marriage go on, Hideko throws her from the room and tries to hang herself. Sook-hee saves her and both admit to their plots. Hideko helps Sook-hee write a letter to her family to say she has teamed up with Hideko, and to hatch a plot to get Hideko and Sook-hee away from the men who have been manipulating them. Hideko shows Sook-hee the books she was forced to read and Sook-hee begins destroying the library. Hideko calls Sook-hee “her savior” and joins in destroying her uncle’s collection.
Sook-hee’s friend Bok-soon sets a fire at the asylum and poses as a firefighter to rescue Sook-hee. Hideko poisons Fujiwara’s wine, causing him to pass out while she takes the money and leaves. The women reunite and flee together, disguising Hideko as a man to avoid detection.
Kouzuki captures Fujiwara upon receiving a letter from Hideko detailing Fujiwara’s deception. He tortures Fujiwara in his cellar with his collection of antique bookmaking tools and presses him for sexual details about his niece. Fujiwara makes up a story about their wedding night but a flashback shows that he watched Hideko masturbate before cutting her hand on a knife to stain her sheets, refusing to consummate the marriage. When Kouzuki presses for more details, Fujiwara convinces him to give him one of his cigarettes. After smoking, a disgusted Fujiwara refuses to give further details. Kouzuki notices the cigarettes are producing blue smoke. Fujiwara reveals that his cigarettes had been laced with mercury and the toxic gas within the smoke kills them both.
On a ferry to Shanghai, China, Sook-hee and Hideko celebrate their newfound freedom by making love once again.