“There was one more, who came after they did and joined them . . . and then, just now, two more, the pair who usually keep watch outside the house.”
“Did they remain in the study?”
“Yes, sir.”
“And they went away when I came back? A few minutes before, perhaps?”
“Yes, sir.”
“That will do.”
The woman left the room. Daubrecq returned to his letter-writing. Then, stretching out his arm, he made some marks on a white writing-tablet, at the end of his desk, and rested it against the desk, as though he wished to keep it in sight. The marks were figures; and Lupin was able to read the following subtraction-sum:
“9 − 8 = 1”
And Daubrecq, speaking between his teeth, thoughtfully uttered the syllables:
“Eight from nine leaves one.... There’s not a doubt about that,” he added, aloud. He wrote one more letter, a very short one, and addressed the envelope with an inscription which Lupin was able to decipher when the letter was placed beside the writing-tablet: