I stood pondering, for no explanation that would fit the facts seemed possible. I should have considered the young fellow's story only an attempt to gain a little reputation for pluck, if in any way I could have accounted for the appearance and disappearance of the robbers. Yet to suppose--which seemed the only other horn to the dilemma--that the son and guests of the vice-president of the Missouri Western, and one of our own directors, would be concerned in train-robbery was to believe something equally improbable. Indeed, I should have put the whole thing down as a practical joke of Mr. Cullen's party, if it had not been for the loss of the registered letters. Even a practical joker would hardly care to go to the length of cutting open government mail-pouches; for Uncle Sam doesn't approve of such conduct. Whatever the explanation, I had enough facts to prevent me from wasting more time on that alkali plain. Getting the men and horses back onto the cars, I jumped up on the tail-board and ordered the runner to pull out for Flagstaff. It was a run of seven hours, getting us in a little after eight, and in those hours I had done a lot of thinking which had all come to one result,--that Mr. Cullen's party was concerned in the hold-up. The two private cars were on a siding, but the Cullens had left for the Grand Cañon the moment they had arrived, and were about reaching there by this time. I went to 218 and questioned the cook and waiter, but they had either seen nothing or else had been primed, for not a fact did I get from them. Going to my own car, I ordered a quick supper, and while I was eating it I questioned my boy. He told me that he had heard the shots, and had bolted the front door of my car, as I had ordered when I went out; that as he turned to go to a safer place, he had seen a man, revolver in hand, climb over the off-side gate of Mr. Cullen's car, and for a moment he had supposed it a road agent, till he saw that it was Albert Cullen. "That was just after I had got off?" I asked. "Yis, sah." "Then it couldn't have been Mr. Cullen, Jim," I declared, "for I found him up at the other end of the car." "Tell you it wuz, Mr. Gordon," Jim insisted. "I done seen his face clar in de light, and he done go into Mr. Cullen's car whar de old gentleman wuz sittin'." That set me whistling to myself, and I laughed to think how near I had come to giving nitroglycerin to a fellow who was only shamming heart-failure; for that it was Frederic Cullen who had climbed on the car I hadn't the slightest doubt, the resemblance between the two brothers being quite strong enough to deceive any one who had never seen them together. I smiled a little, and remarked to myself, "I think I can make good my boast that I would catch the robbers; but whether the Cullens will like my doing it, I question. What is more, Lord Ralles will owe me a bottle." Then I thought of Madge, and didn't feel as pleased over my success as I had felt a moment before.