"Did she make the appointment?" The thought was no sooner uttered than it gave place to another equally as suggestive, for just then thoughts raced through Sam's brain with amazing rapidity. "Or, rather, was she not compelled to meet the stranger by some power which he had obtained over her--some secret of her life which she feared--a deathly fear, of disclosure, and which this man knew, and its power he knew only too well, how to wield." The more he thought about it, the more the mystery, for such it appeared to him, deepened. He determined to fathom it. Inured to a rough, open-air life on the Texas plains, his constitution was hard and tough, and well seasoned for the job presented--and, it must be confessed, it was to his liking. Sam felt his blood tingle as his enthusiasm rose to the prospect of a genuine adventure, and he hurried along, over the soft, yielding grass, to catch sight of the fellow ahead. A clump of low bushes suddenly confronted him. It was an unusually dark spot, and then, for the first time, he thought of the ugly knife the stranger had displayed, and realized that he himself was unarmed. He almost halted--wary of running into an ambush, and cautiously made a wide detour, meanwhile alert for any sudden surprise from the direction of the bush. Discovering no sign of a crouching figure there, he hastened on, and finally caught sight of a moving shadow, as it crossed a faint shaft of light shot from a window of a dwelling on Ford street, to his left. "Ah, I guess so. That's the party," he muttered to himself, and from that moment Sam was as keen on the trail as a sleuth on the scent, never losing sight of his quarry, but himself avoiding, as he believed, discovery. Occasionally, as the moon cleared from an obscuring cloud, he could make out the man halting under the shelter of a fir or clump of saplings, evidently to listen for sounds of a pursuer, and then, seemingly satisfied, again move on. So far the direction of his course was toward the reservoir, but of a sudden he turned, and sharply cutting across Sam's front, swiftly entered the deep gloom of a cluster of cedars, where he was lost to the eyes of the pursuer. It was plain that his man intended to avoid exit by the main gate, or by Park avenue, a circumstance to cause Sam keen chagrin, for he hoped by an adroit move to get a good square look at the fellow's face as he would pass under the entrance arc light.