This apathy lasted for four days—the four days most important of any in the lives of himself, of Gilead Beck, and of Lawrence Colquhoun. For the fortunes of all hung upon his shaking it off, and he did not shake it off.
On the second day, the day when he got the letter telling him that his wife had been in Colquhoun's chambers while he was there, he sent for a private detective.
He put into his hands all the letters.
"Written by a woman," said the officer. "Have you any clue, sir?"
"None—none whatever. I want you to watch. You will watch my wife and you will watch Mr. Colquhoun. Get every movement watched, and report to me every morning. Can you do this? Good. Then go, and spare neither pains nor money."
The next morning's report was unsatisfactory. Colquhoun had gone to the Park in the afternoon, dined at his club, and gone home to his chambers at eleven. Mrs. Cassilis, after dining at home, went out at ten, and returned early—at half-past eleven.
But there came a letter from the anonymous correspondent.
"You are having a watch set on them. Good. But that won't find out the Scotch secret. She was in his room while you were there—hidden somewhere, but I do not know where."
He went home to watch his wife with his own eyes. He might as well have watched a marble statue. She met his eyes with the calm cold look to which he was accustomed. There was nothing in her manner to show that she was other than she had always been. He tried in her presence to realise the fact, if it was a fact. "This woman," he said to himself, "has been lying hidden in Colquhoun's chambers listening while I talked to him. She was there before I went; she was there when I came away. What is her secret?"
What, indeed! She seemed a woman who could have no secrets, a woman whose life from her cradle might have been exposed to the whole world, who would have found nothing but cause of admiration and respect.