«In that case,» Dupin said, «take out your checkbook and write me a check for fifty thousand francs. When you have signed the check, I will give you the letter.» Germont looked at Dupin with his mouth open. His eyes seemed to jump out of his head. Then he took out his checkbook and pen, and wrote a check for fifty thousand francs. He gave it to Dupin. My friend examined the check carefully and put it in his pocket. Then he unlocked a drawer of his desk, took out the letter, and gave it to Germont. The policeman's hands shook as he opened the letter. He read it quickly. Then he put it in his pocket and ran out of the room without saying a word. «Dupin!» I said, as I turned to my friend. «How did you solve the mystery?» «It was simple, my friend,» he said. «Germont and his policemen could not find the letter, because they did not try to understand the mind of the man who stole it. Instead, they looked for the letter where they would have hidden it. Mr. D'Arcy is not a policeman. He is, however, very intelligent. He knew the police would search his apartment. He also knew how police think. So, he did not hide the letter where he knew they would look for it.»