“Because he did not dare take the biggest risk of all⁠—that of keeping it on his own person.”

“I don’t understand.”

“Look at it from his point of view. I have discovered that there were only five short minutes in which he could have taken it⁠—the five minutes immediately before our own arrival on the scene, for before that time Annie was brushing the stairs, and would have seen anyone who passed going to the right wing. Figure to yourself the scene! He enters the room, unlocking the door by means of one of the other doorkeys⁠—they were all much alike. He hurries to the despatch-case⁠—it is locked, and the keys are nowhere to be seen. That is a terrible blow to him, for it means that his presence in the room cannot be concealed as he had hoped. But he sees clearly that everything must be risked for the sake of that damning piece of evidence. Quickly, he forces the lock with a penknife, and turns over the papers until he finds what he is looking for.