In Daphne Du Maurier's novel, Rebecca, noir fiction is found surrounding the reopening of the death of Rebecca de Winter, Maxim de Winter's first wife.
Noir fiction is a sub-genre of "hardboiled" crime fiction, where the detective is called in to solve a mystery or murder. The detective is "tough," and faces all kinds of danger, but is not a part of the family. The distinction with noir fiction is that the investigation taking place usually does involve someone close to the situation.
...the protagonist is usually not a detective, but instead either a victim, a suspect, or a perpetrator...tied directly to the crime, not an outsider...
There is often there is a sexual component involved as well. There is an...
...emphasis on sexual relationships and the use of sex to advance the plot and the self-destructive qualities of the lead characters.
These details can be found in Rebecca. The narrator, the new Mrs. de Winter, is the only one in the house who is curious enough about her predecessor to investigate to find clues as to who Rebecca really was. In a discussion with her husband, Maxim describes a woman's mind—thinking perhaps of Rebecca:
...what goes on in the twisted, tortuous minds of women would baffle anyone.
This might have piqued the narrator's curiosity. She has only the delusional details provided by the crazed Mrs. Danvers. Maxim is not interested in speaking of Rebecca at all. The narrator fill the prerequisite of noir fiction: she tries to solve something of the mystery of Rebecca, and she is closely involved, not an outsider like a police detective would be.
When a boat washes ashore, Maxim admits that the woman's body that he identified as Rebecca's was not his wife at all.
There was never an accident. Rebecca was not drowned at all. I killed her. I shot Rebecca in the cottage in the cove...I hated her, I tell you, our marriage was a farce from the very first.
The ensuing investigation reopens her cause of death; Maxim is a suspect, and what really happened between Rebecca and Maxim haunts Maxim, and disturbs the narrator greatly on Maxim's behalf.
Jack Favell, Rebecca's cousin, insists that Rebecca was murdered—he says they were to have run away together the day of her death. Favell, too, fills a requirement of noir fiction. He, too, is investigating Rebecca's death and he is an insider. He had been having an adulterous affair with Rebecca; this is something that advanced the plot (driving a wedge between Maxim and Rebecca), as Rebecca threw the fact in Maxim's face, infuriating him. This affair gives Rebecca the ammunition she needs to drive Maxim to kill her: she knows she is dying, and chooses to "take Maxim with her."
I remembered her eyes as she looked at me before she died. I remembered that slow treacherous smile. She knew this would happen even then. She knew she would win in the end.
Favell's connection to Rebecca (noir fiction) drives his character to search for proof that Rebecca was murdered by Maxim. Favell even tries to blackmail Maxim, but Maxim will have none of it, bringing the situation to the magistrate (the law). Visiting Rebecca's doctor, they find she had cancer, and faced a long and painful death. The magistrate believes this proved that Rebecca killed herself; Maxim later tells his wife that this was probably why Rebecca "goaded him into killing her."