This investigation, perfunctory as it was, decided us against any idea of Mannering's complicity, and I fell back upon the theory that the diamond merchant must have communicated his methods to some one else. We sought him out in the city, and he assured us that he had never before referred to the subject. He did not object to supplying us with the names of his acquaintances who owned cars, and either Forrest or myself made inquiries concerning every one of them. All were to no purpose. When we had finished, we were no nearer discovering anything concerning the Pirate than we were when we had begun.
Then occurred an incident which should have opened our eyes, if anything possibly could have done so, to the personality of the Pirate. But again we were absolutely blind.
It was the second week of May, and since, in spite of continued fine weather, our unknown terror remained in the seclusion of his hiding-place, wherever it might be, I had persuaded Forrest to come with me for a run one afternoon as far as Cambridge, proposing to return after sunset.
The roads were beginning to be a little dusty, but altogether we had a very pleasant journey without any incident of note. We left the university town about nine, reckoning upon getting home comfortably before midnight. There was a bright slice of moon shining, and we did the dozen miles before reaching Royston at a decent pace. We went slowly over the hilly road out of Royston and had passed over the worst of it, and I had just put on a higher speed, when I fancied I heard the distant hum which once heard could never be mistaken for anything else. Forrest heard it at the same time as myself.
"Pull up at the side of the road," he cried. "The car must not be damaged."
I obeyed, running the bonnet into the hedge and leaving the back of the car extended over the footpath. Meanwhile, Forrest had drawn his revolver from his pocket, and the moment I brought the car to a standstill I followed his example.
"Don't stand on ceremony," advised my companion; "shoot on sight!"
The words were scarcely out of his mouth when our enemy made his appearance, coming from the direction of Buntingford. Whether he had any intention of stopping and robbing us, I have no means of telling, but I think not, for he was travelling at his most rapid pace, and gave no signs of slackening as he approached. Once more I was astonished at the wonderful steadiness of his machine. He passed us in a flash, the car running as evenly as if it were upon rails. In fact I paid so much attention to this, that I was too late to fire with any prospect of hitting him. Forrest was more alert. As the Pirate swooped by, the detective's Colt spoke twice. So far as we could see, the shots took no effect, for he did not move an inch.
"No luck," muttered my companion, as the hum of the Pirate's car died away in the distance.
I held up a warning finger. "Hush!" I said.