Rosaura at 10 O’Clock

The story begins at La Madrileña, a boardinghouse in Buenos Aires, where the owner Mrs. Milagros lives with her three daughters and other residents. Camilo Canegato, a shy painter and portrait restorer, has been living there for 12 years. The setting establishes a quiet, intimate environment where the main characters' lives intersect.

Camilo starts receiving perfumed love letters from a woman named Rosaura, sent via the 10pm mail. He also keeps a painting of Rosaura, depicting her as young and beautiful, hidden in his room. These mysterious letters and the painting hint at Rosaura’s romantic interest in Camilo.

Mrs. Milagros and her daughters read Rosaura’s passionate letters without Camilo’s knowledge, and they find out about her life with her aunt and wealthy, dominating father. They learn that Rosaura is being forced into an unwanted marriage, revealing her tragic circumstances.

Rosaura unexpectedly arrives at La Madrileña seeking Camilo. Mrs. Milagros recognizes her from the painting and welcomes her warmly, while Camilo is shocked and icy toward her. Rosaura’s visit sets the stage for their wedding and her subsequent tragic fate.

Camilo and Rosaura marry, but their happiness is short-lived when Rosaura is found dead in a hotel room after their wedding night. David, who followed them, discovers Rosaura’s body and inform the others, leading to suspicions of Camilo’s involvement.

The police investigate Rosaura’s death by questioning the residents of La Madrileña and reading an unmailed letter from Rosaura to her aunt. They uncover Rosaura’s true identity as Maria and her troubled past, complicating Camilo’s innocence.

It is revealed that Maria, Rosaura’s real identity, was the niece of Camilo’s laundry lady. She was coerced into sex work by her aunt’s associates and later imprisoned for a crime. After five years, she escaped from prison and sought Camilo for help with money, not love.

Police discover that Camilo wrote the love letters to Matilde, Mrs. Milagros’ daughter, to express his romantic feelings. Camilo’s photo of Maria was used as Rosaura’s portrait, and her arrival at La Madrileña was coincidental, not premeditated.

On their wedding night, Rosaura (Maria) taunted Camilo about alimony if he divorced her, which enraged him. He began to strangle her but couldn’t bring himself to kill her, then ran out into the street in a daze, where David was waiting outside.

The hotel where Camilo and Maria stayed was owned by the Turk, a man connected to the prostitution ring involved with Maria. Unbeknownst to Camilo, it was the Turk who checked them in, linking the murder to the criminal gang.

The police conclude that the Turk and his associates are responsible for Rosaura’s murder and arrest them along with her pimp and friend. Camilo is cleared of suspicion, restoring his innocence in the tragic death of Rosaura.