When a fisherman finds a large, heavy chest, he sells it to the Caliph Harun al-Rashid. To everyone's horror, the caliph orders the chest opened, revealing a woman's corpse, sliced into quarters. The caliph demands that his vizier, Ja'far, locate the murderer and solve the crime within three days. If Ja'far fails, he will be executed.
Predictably, Ja'far fails; there are no clues or hints to guide his search. However, right before his execution, two people - the young husband and the old father - arrive claiming responsibility for the murder. Each man insists he is the guilty party, but only the young man can correctly describe the chest in which the woman was found. The young man then reveals he was the woman's husband, and the older man her father, who was trying to save his son-in-law by feigning guilt.
Through a series of stories, the young man explains the circumstances of the murder. After falling terribly ill one day, the young man's wife requested an extremely rare apple that he could not locate at any market. Determined to help her, he traveled two weeks to reach Basra, where he found the correct apples in the caliph's orchard. He gathered three of them and returned home.
However, his wife had in the meantime grown too ill to eat. One day soon afterwards, he spotted a slave (Ja'far's slave, though the young man did not know this) carrying one of the fruits, and confronted him. The slave revealed that his girlfriend had gifted him the apple after her husband had found them. Outraged at his wife's apparent infidelity, he investigated to discover one apple indeed missing, and then killed her for her crime. He rid himself of the evidence by cutting her body into pieces, locking them in a chest, and abandoning it in the river.
Here comes a twist, though - he later learned that it was his son who stole the apple and then gave it to the vizier's slave, telling of his father's quest in the process. Clearly, the slave had lied simply to cause mischief.
After describing his unfortunate story, the young man requests that the caliph execute him for his crime, but the caliph is sympathetic. Instead, he sends Ja'far to find the mischievous slave, again at the risk of his own execution.
Once again, the vizier fails. Before leaving for his execution, he hugs his youngest daughter - and finds one of the apples in her pocket. She admits that she received it from one of their slaves, and Ja'far realizes one of his own slaves is the culprit. He thereby avoids death, and begs the caliph spare his slave as well. In exchange, he promises to tell the caliph a story called "Tale of Núr al-Dín Alí and His Son Badr al-Dín Hasan."
This story is typically regarded as one of the original murder mystery/whodunit stories that are so popular today. It begins with the discovery of a body, then introduces a pair of suspects, and continues along a series of twists until the final culprit is revealed. The difference between this and a more typical whodunit, though, is that our detective character (Ja'far the vizier) does not actually succeed in solving any crime; he simply happens upon the answer when he discovers the apple in his daughter's pocket.
The story makes great use of twists, which is today a commonly-used tactic for keeping readers engaged, interested, and alert. In both instances, just when Ja'far is about to be executed, some big reveal changes the course of the story. First, the two men show up and take the blame. Then, he discovers that his own slave is guilty. Plot twists are essential components to any story that has elements of detective fiction, and of most successful stories in general. One of the great virtues of this collection is that it employs so many elements of good storytelling in a time before any professional criticism was available. That implies that the standards of storytelling (often cited to Aristotle's Poetics) developed before any criticism indicated their value.
Though the story focuses mainly on the young man and his description of events, the caliph is an interesting character in his own right. His sympathies seem quite mixed; on one hand, he is willing to forgive the young man even though he killed his wife, but on the other, twice threatens his vizier with execution for failing to complete nearly impossible tasks. This story thereby confirms the idea that the caliph, during the Islamic Golden Age, was the final say on everything; not once does anyone question his decisions, though they seem markedly contradictory.
The caliph is used in several of the stories in the collection, both because his position was so powerful and because it allows for more levels of storytelling. This story is one of the most complex in this regard. The story of "The Three Apples" is a first-level story, meaning it is being told directly from Scheherazade to Shahrayar. However, it serves as its own frame - at the end of the tale, Ja'far tells his own second-level story, "Tale of Núr al-Dín Alí and His Son Badr al-Dín Hasan." Interestingly, Ja'far tells this story in order to save his slave, much as Scheherazade is telling her stories in order to save her own life (and those of other women).
Further, the story has more directly embedded stories within it - those told by the young man. He is telling his story for his life, and successfully earns a pardon because of the way he tells his history. In these ways, Sheherazade is constructing parallels to her own situation, in which her stories are expected to improve a situation and save lives. This use of multi-levelled storytelling continues in various ways throughout the collection; in some versions, many stories are told to the caliph. In between those second-level stories, the narrative returns to the first-level story set in the caliph's court, as he then decides to pardon Ja'far and his slave. In many ways, this is Scheherazade subtly suggesting that her own listener show mercy. As is the case with the frame story, The Arabian Nights does not only relate tales, but comments on them as well, again reminding us that stories are more than just entertainment - they can change or save our lives.
Finally, this story echoes the rather harsh sentiments towards women that are present in many other tales as well. While the woman's murder initially warrants justice, the caliph is quick to forget about her death simply because the husband admits his mistake. Further, the fact that even the woman's father was willing to take the blame for the sake of his son-in-law suggests the extent of the patriarchy at this time. That is particularly appalling, considering how brutally the girl was killed. (Of course, many marriages in higher classes were arranged within the family, meaning the old man might be related to the young man as well.) Either way, it is clear that women were expected to conform to a rather severe set of expectations, much as Sheherazade herself is.