Devil's Dice by William le Queux

My first impulse was to remain outside and watch for any person who might emerge, but I knew that his front windows commanded a wide view of the street and he would soon detect me; and again, if anyone did come out, I should not know whether they came from one of the other flats in the same building. Slowly I walked round to my chambers, contemplating the best course to pursue, and at length came to the conclusion that a midnight vigil would be useless, for it might possibly further arouse my friend's suspicions and so thwart my own efforts.

His refusal to disclose the identity of his guest and his firm determination to keep the visit a secret, convinced me more than ever that by his hand Gilbert Sternroyd had fallen, and that he was endeavouring to get rid of the evidence of his crime. That night I slept but little, and in the morning, remembering Dora's appointment, I resolved to run round and see him before she called. It was my intention to make pretence that I had a conviction that his visitor was a woman, and wished to give him a chance of explaining to me. If he again refused, then I would impart my suspicions to the woman who loved him. I had no desire to cause her pain, but felt it best that she should know the truth. Sooner or later the blow must fall, and I knew alas! that it would crush her.