The Cinema Murder by E. Phillips Oppenheim

A few nights later Philip awoke suddenly to find himself in a cold sweat, face to face with all the horrors of an excited imagination. Once more he felt his hand greedy for the soft flesh of the man he hated, tearing its way through the stiff collar, felt the demoniacal strength shooting down his arm, the fever at his finger tips. He saw the terrified face of his victim, a strong man but impotent in his grasp; heard the splash of the turgid waters; saw himself, his lust for vengeance unsatisfied, peering downwards through the dim and murky gloom. It was not only a physical nightmare which seized him. His brain, too, was his accuser. He saw with a hideous clarity that even the excuse of motive was denied him. It was a sense of personal loss which had driven him out on to that canal path, a murderer at heart. It was something of which he had been robbed, an acute and burning desire for vengeance, personal, entirely egotistical.

It was not the wrong to the woman which he resented, had there been any wrong. It was the agony of his own personal misery. He rose from his bed and stamped up and down his little chamber in a fear which was almost hysterical. He threw wide open the windows, heedless of a driving snowstorm. The subdued murmur of the city, with its paling lights, brought him no relief. He longed frantically for some one who knew the truth, for Elizabeth before any one, with her soft, cool touch, her gentle, protective sympathy. He was a fool to think he could live alone like this, with such a burden to bear! Perhaps it would not be for long. The risks were many. At any moment he might hear the lift stop, steps across the corridor, the ring at his bell, the plainly-clad, businesslike man outside, with his formal questions, his grim civility. He fumbled about in his little dressing-case until he came to a small box containing several white pills. He gripped them in his hand and looked around, listening.