"As a matter of fact, the risk is comparatively small," Grady said. "It was only by a pure accident that we got on the inside track of this matter. You see, the coins are of actual face value, they are most beautifully made, and, indeed, would pass anywhere. Let me tell you that every sovereign contains a certain amount of alloy which reduces its actual value to about eighteen and threepence. Now you can see where the profit comes in. Supposing these men turn out a couple of thousand sovereigns a day—no very difficult matter with a plant like theirs; and, of course, the money can be disposed of with the greatest possible ease. This leaves a profit of a hundred and seventy-five pounds a day. When I have said so much, I think I have told you everything. Don't you admire the ingenuity of an idea like this?"

It was all perfectly plain now—indeed, the mystery appeared to be ridiculously simple now that it was explained.

"And what are you going to do now?" Venner asked.

Grady explained that the next step would be the arrest of Fenwick and his gang at Merton Grange. For that purpose it would be necessary to enlist the assistance of the local authorities. And in no case did the American detectives purpose to effect the arrest before night. So far as Venner was concerned, he was quite at liberty to accompany the Americans on their errand; at the same time they let him infer that here was a situation in which they preferred his room to his company.

"As you will," Venner smiled. "So far as I am concerned, I am going to get back to Canterbury as soon as I can. With all your preparations you have an exceedingly clever man to deal with, and it is just possible that by this time Fenwick already knows that you have laid the messenger by the heels. Men of that sort never trust one another, and it is exceedingly probable that Blossett has been watched."

Grady and Egan admitted this possibility cheerfully enough. Doubtless they had made plans which they did not care to communicate to Venner. He left them presently, only to discover to his annoyance that he had just missed a train to Canterbury, and that there was not another one till nearly six o'clock. It was quite dark when he stepped out of the carriage at Canterbury Station and stood debating whether he should walk as far as the lodgings he had taken near Merton Grange, or call a cab. As he was idly making up his mind, he saw to his surprise the figure of the handsome cripple descending from the next carriage. He noted, too, that the cripple did not seem anything like as feeble as before, though he appeared to be glad enough to lean on the arm of a servant. At the same moment Le Fenu was joined by Evors, who came eagerly forward and shook him warmly by the hand. What these two were doing here, and what they had in their minds, it was not for Venner to say. He wondered what they would think if they knew how close he was, and how deeply interested he was in their movements. He hung back in the shadow, for just then he did not want to be recognised by Le Fenu.

"What a queer tangle it all is," he said to himself. "If I spoke to Le Fenu, he would recognise me in a moment as an old friend of his father's. I wonder what he would say to me if he knew I was his brother-in-law —and Evors, too. Imagine their astonishment if I walked up to them at this moment. Still, on the whole, I think I prefer to watch their movements. If they are going to thrust their heads into the lion's mouth, perhaps I may be able to stand by and render some assistance."

It was as Venner had anticipated, for presently Le Fenu and Evors entered a cab and gave the driver directions to take them as far as Merton Grange. Venner made up his mind that he could do no better than follow their example.

The cab stopped at length outside the lodge gates, where Evors and Le Fenu alighted, and walked slowly up the drive. It was rather a painful effort for Le Fenu, but he managed it a great deal better than Venner had anticipated. They did not enter the house by the front door—on the contrary, they crept round a small side entrance, beyond which they vanished, leaving Venner standing on the grass wondering what he had better do next.

Meanwhile, Evors led the way down a flight of stairs till he emerged presently in a corridor. With his companion on his arm he walked to the little room at the end and boldly flung open the door.