He felt that, if discovered, he could do little in his defence and against assault; and though without a thought but that of fierce struggle to the last, his reason taught him to perceive with how little hope of success.
As the assassins continued to advance, he could distinctly trace every change of expression in their several countenances.

In that of Rivers, linked with the hideousness that his wound conferred upon it, he noted the more wicked workings of a spirit, the fell character of whose features received no moderate exaggeration from the dim and flickering glare of the lamp which his hand unsteadily carried.

The whole face had in it something awfully fearful.

He seemed, in its expression, already striking the blow at the breast of his victim, or rioting with a fiendish revenge in his groaned agonies.

A brief dialogue between his companion and himself more fully describes the character of the monster.
"Stay--you hurry too much in this matter," said Munro, putting his hand on that of Rivers, and restraining his steps for a moment as he paused, seemingly to listen.