“One metre⁠ ⁠… two metres⁠ ⁠… three metres.⁠ ⁠… Here is the door.⁠ ⁠… Mon Dieu , how easy it is! Only a small, simple bolt now separates me from the chamber, and I know that the bolt is located exactly one metre, forty-three centimeters, from the floor. So that, thanks to a small incision I am about to make, I can soon get rid of the bolt.”

He drew from his pocket the necessary instruments. Then the following idea occurred to him:

“Suppose, by chance, the door is not bolted. I will try it first.”

He turned the knob, and the door opened.

“My brave Lupin, surely fortune favors you.⁠ ⁠… What’s to be done now? You know the situation of the rooms; you know the place in which the countess hides the black pearl. Therefore, in order to secure the black pearl, you have simply to be more silent than silence, more invisible than darkness itself.”