"There is a mark there below the hilt of that arrow," she said curiously. "Yes, and a tiny note in ink."
For a moment a little gift of vision was vouchsafed to Jim Frobisher, born, no doubt, of his perplexities and trouble. A curtain was rung up in his brain. He saw no more than what was before him—the pretty group about the table in the gold of the May morning, but it was all made grim and terrible and the gold had withered to a light that was grey and deathly and cold as the grave. There were the two girls in the grace of their beauty and their youth, daintily tended, fastidiously dressed, bending their shining curls over that plate of the poison arrows like pupils at a lecture. And the man delivering the lecture, so close to them, with speech so gentle, was implacably on the trail of murder, and maybe even now looked upon one of these two girls as his quarry; was even now perhaps planning to set her in the dock of an Assize Court and send her out afterwards, carried screaming and sobbing with terror in the first grey of the morning to the hideous red engine erected during the night before the prison gates. Jim saw Hanaud the genial and friendly, as in some flawed mirror, twisted into a sinister and terrifying figure. How could he sit so close with them at the table, talk to them, point them out this and that diagram in the plates, he being human and knowing what he purposed. Jim broke in upon the lecture with a cry of exasperation.
"But this isn't a poison! This is a book about a poison. The book can't kill!"
At once Hanaud replied to him:
"Can't it?" he cried sharply. "Listen to what Mademoiselle said a minute ago. Below the hilt of this arrow marked 'Figure F,' the Professor has written a tiny note."
This particular arrow was a little different from the others in the shape of its shaft. Just below the triangular iron head the shaft expanded. It was as though the head had been fitted into a bulb; as one sees sometimes wooden penholders fine enough and tapering at the upper end, and quite thick just above the nib.
"'See page 37,'" said Hanaud, reading the Professor's note, and he turned back the pages.
"Page 37. Here we are!"
Hanaud ran a finger half-way down the page and stopped at a word in capitals.
"Figure F."