"I felt sure," he went on, "that for a day or two Helzephron would show himself in London. Knowing what we know—or at least suspect—such a move was a certainty. He is in the habit of coming here. He booked his usual seat at this restaurant, and his usual box at the Parthenon Theatre—and for reasons obvious to you and me, if to no one else in the world! I confess to an anxiety to look upon this man."
"You have had this corner darkened?" I said quickly. "No one can see us here?"
"Not clearly. And Helzephron would not know who we are if he did see us. But, as he is sure to come upon us in Cornwall, it is better to take no risks. To that end I have had a little device arranged for us which proved of great service to me once in Chicago."
He bent forward to the mass of ferns and flowers in the centre of the table, disarranging the greenery at its base. At once a green-painted tube became visible, and then a slanting mirror, the size of a postcard.
"What on earth is that?" I whispered.
"An adaptation of the periscope!" he replied, taking a magnifying glass from his pocket, adjusting it, and bending over the mirror. "The lens is focussed upon Helzephron's table. With this magnifier I enlarge the image in the mirror. Ah! So that is the honourable gentleman!"
A faint hissing noise came from him. His face stiffened into fixed and horrible intentness as he stared through his magnifier at the little oblong of mirror.
"Shi-ban, Go-ban, hei!" he muttered. "There are two, then. I expect the younger man is the Honourable Herbert Gascoigne, of whom we have heard!"
The hissing noise continued, the ecstasy of attention did not relax for two or three minutes.
At last Danjuro looked up. His face, which had seemed carved out of jade, relaxed.