On an autumn evening, the narrator rests with his friend Auguste Dupin and recalls his investigations into “Murders on Morgue Street” and “The Secrets of Maria Roger”. Suddenly, their old acquaintance, the prefect of the Paris police, comes to them. The law enforcer wants to consult with Dupin about a matter of national importance, which causes him a lot of trouble.

For the prefect, it is both simple and complex at the same time. Before his story, the prefect asks the audience to keep the information secret. A letter of the highest importance was stolen from the royal apartments of the young lady, more precisely, replaced by another, less important. The kidnapper is famous - they saw how he took the document - this is Minister D. In addition, it is known that the document is still with him. The minister uses the document for the sake of power, not knowing the measures, that is, blackmailing the girl. The victim cannot receive the letter back, so she confided in the prefect.

Based on this, the prefect made two conclusions: first, the power gives possession of the document, and not its use; second, it is important that the owner can provide it immediately and be able to destroy it immediately. Dupin agrees with his conclusions.

Police officers conduct a thorough search in the minister’s house, secretly from himself, but find nothing.For three months, the prefect personally searches the official’s chambers almost nightly, but to no avail. The ministers are stopped twice by imaginary robbers and try to find a letter, but this also does not bear fruit. Finally, the prefect reads the narrator and Dupin the exact description of the letter, and then leaves.

A month later, the policeman again visits Dupin. He is in deepest despondency and despair. To those who help, he is ready to write out his personal check for 50 thousand francs. After giving the policeman vague advice on the steps that should be taken, Dupin asks to write him a check, after which he is ready to hand the prefect a letter. The amazed cop writes him a document and, having received the letter, runs away without saying a word.

Meanwhile, the detective gives explanations to his friend. If the letter were indeed hidden in the usual way, then the prefect would certainly have found it. In order to hide something well, it is better not to hide it at all. Dupin made two visits to the Minister: the first time he noticed the letter in the most visible place, the second with the help of a distracting maneuver replaced the letter with an exact copy. The substitution of the letter was dictated by security considerations, Dupin's political preferences, and also by the old nasty act of the minister in relation to the detective.