The miles rolled beneath, yet there was no token of the Du Vallon that was to "run slowly up the hill" until overtaken by the industrious writer of postcards. At the utmost, the French car was given some twelve or thirteen minutes' start, which meant seven or eight miles to a high-powered automobile urged forward with the determination Medenham himself was displaying. Marigny's chauffeur, therefore, must have dashed through that Titanic cleft in the limestone at a speed utterly incompatible with his employer's excuse of sightseeing. Of course, it would be an easy matter for Marigny to enlist Miss Vanrenen's sympathies in the effort of a first-rate engine to conquer the adverse gradient. She would hardly realize the rate of progress, and, from where she was seated, the speed indicator would be invisible unless she leaned forward for the express purpose of reading it. Medenham was sure that the Mercury would catch the Du Vallon long before Bristol was reached, but when the last ample fold of the bleak plateau spread itself in front, and his hunter's eyes could discern no cloud of dust lingering in the still air where the road dipped over the horizon, he began to doubt, to question, to solve grotesque problems that were discarded ere they had well taken shape. Oddly enough, there came no more expostulation from Mrs. Devar. Like the majority of nervous people, she was quelled by the need of placing complete trust in one who understood his work. While Medenham was still searching the sky-line for signs of the vanished car, she did show some interest in his quest. He felt, since he could not see, that she half rose and looked over his head, bent low behind the partial shelter afforded by a glass screen. Then she settled back in the seat, and drew a rug comfortably around her knees. For some reason, she was strangely content. The incident supplied food for active thought. So she felt safe! That which she dreaded as the result of a too strenuous pursuit could not now happen! Then what was it? Medenham swept aside the fantasy that Mrs. Devar knew the country well enough to be able to say precisely when and where she might be sure of his failure to snatch Cynthia from that hidden evil the nature of which he could only guess at. Her world was the artificial one of hotels, and shops, and numbered streets--in the real world, of which the lonely wastes of the Mendips provided no meager sample, she was a profound ignoramus, a fat little automaton equipped with atrophied senses. But she blundered badly in composing herself so cozily for the remainder of the run to Bristol. Medenham had dwelt many months at a time in lands where just such simple indications of mood on the part of man or beast had meant to him all the difference between life and death. So now, if ever, he became doubly alert; his eyes were strained, eager, peering; his body still as the wild creatures which he knew to be skulking unseen behind many a rock and grass tuft passed on the way.