“Oh, yes, you have,” said he, handing me one. “This will do very well. It is almost a facsimile.”

“And who do you expect will answer this advertisement?”

“Why, the man in the brown coat — our florid friend with the square toes. If he does not come himself, he will send an accomplice.”

“Would he not consider it as too dangerous?”

“Not at all. If my view of the case is correct, and I have every reason to believe that it is, this man would rather risk anything than lose the ring. According to my notion he dropped it while stooping over Drebber’s body, and did not miss it at the time. After leaving the house he discovered his loss and hurried back, but found the police already in possession, owing to his own folly in leaving the candle burning. He had to pretend to be drunk in order to allay the suspicions which might have been aroused by his appearance at the gate. Now put yourself in that man’s place. On thinking the matter over, it must have occurred to him that it was possible that he had lost the ring in the road after leaving the house. What would he do do then? He would eagerly look out for the evening papers in the hope of seeing it among the articles found. His eye, of course, would light upon this. He would be overjoyed. Why should he fear a trap? There would be no reason in his eyes why the finding of the ring should be connected with the murder. He would come. He will come. You shall see him within an hour.”

“And then?” I asked.

“Oh, you can leave me to deal with him then. Have you any arms?”

“I have my old service revolver and a few cartridges.”

“You had better clean it and load it. He will be a desperate man; and though I shall take him unawares, it is as well to be ready for anything.”

I went to my bedroom and followed his advice. When I returned with the pistol, the table had been cleared, and Holmes was engaged in his favourite occupation of scraping upon his violin.

“The plot thickens,” he said, as I entered; “I have just had an answer to my American telegram. My view of the case is the correct one.”

“And that is?” I asked eagerly.

“My fiddle would be the better for new strings,” he remarked. “Put your pistol in your pocket. When the fellow comes, speak to him in an ordinary way. Leave the rest to me. Don’t frighten him by looking at him too hard.”

“It is eight o’clock now,” I said, glancing at my watch.

“Yes. He will probably be here in a few minutes. Open the door slightly. That will do. Now put the key on the inside. Thank you! This is a queer old book I picked up at a stall yesterday — De Jure inter Gentes — published in Latin at Liege in the Lowlands, in 1642. Charles’s head was still firm on his shoulders when this little brown-backed volume was struck off.”

“Who is the printer?”

“Philippe de Croy, whoever he may have been. On the flyleaf, in very faded ink, is written ‘Ex libris Guliolmi Whyte.’ I wonder who William Whyte was. Some pragmatical seventeenth century lawyer, I suppose. His writing has a legal twist about it. Here comes our man, I think.”

‘You’re quite sure it’s all right for you?’

‘Perfectly all right.’

And again they were still. The launch twanged and hooted, somebody was singing. Then as if the night smashed, suddenly there was a great shout, a confusion of shouting, warring on the water, then the horrid noise of paddles reversed and churned violently.

Gerald sat up, and Gudrun looked at him in fear.

‘Somebody in the water,’ he said, angrily, and desperately, looking keenly across the dusk. ‘Can you row up?’

‘Where, to the launch?’ asked Gudrun, in nervous panic.

‘Yes.’

‘You’ll tell me if I don’t steer straight,’ she said, in nervous apprehension.

‘You keep pretty level,’ he said, and the canoe hastened forward.

The shouting and the noise continued, sounding horrid through the dusk, over the surface of the water.

‘Wasn’t this BOUND to happen?’ said Gudrun, with heavy hateful irony. But he hardly heard, and she glanced over her shoulder to see her way. The half–dark waters were sprinkled with lovely bubbles of swaying lights, the launch did not look far off. She was rocking her lights in the early night. Gudrun rowed as hard as she could. But now that it was a serious matter, she seemed uncertain and clumsy in her stroke, it was difficult to paddle swiftly. She glanced at his face. He was looking fixedly into the darkness, very keen and alert and single in himself, instrumental. Her heart sank, she seemed to die a death. ‘Of course,’ she said to herself, ‘nobody will be drowned. Of course they won’t. It would be too extravagant and sensational.’ But her heart was cold, because of his sharp impersonal face. It was as if he belonged naturally to dread and catastrophe, as if he were himself again.

Then there came a child’s voice, a girl’s high, piercing shriek:

‘Di—Di—Di—Di—Oh Di—Oh Di—Oh Di!’

The blood ran cold in Gudrun’s veins.

‘It’s Diana, is it,’ muttered Gerald. ‘The young monkey, she’d have to be up to some of her tricks.’

And he glanced again at the paddle, the boat was not going quickly enough for him. It made Gudrun almost helpless at the rowing, this nervous stress. She kept up with all her might. Still the voices were calling and answering.

‘Where, where? There you are—that’s it. Which? No—No–o–o. Damn it all, here, HERE—’ Boats were hurrying from all directions to the scene, coloured lanterns could be seen waving close to the surface of the lake, reflections swaying after them in uneven haste. The steamer hooted again, for some unknown reason. Gudrun’s boat was travelling quickly, the lanterns were swinging behind Gerald.

And then again came the child’s high, screaming voice, with a note of weeping and impatience in it now:

‘Di—Oh Di—Oh Di—Di—!’