"Even so, we are dealing with an old man who is deliberately exposing himself to danger at my request."
Pons took the path so rapidly I was hard put to keep up with him. The mist was thinning a little now and we again saw the beam of light dancing across the ground. Pons halted, taking stock of the situation.
"We must be careful now, Parker. We have to make sure we do not alarm whoever may be concealed out here. Ah, that is better."
For, as we stepped forward from behind a screen of bushes we had a clear view of a ridge some two hundred yards off where old Silas Grimstone was advancing with his torch. Far to the right, invisible behind the hump was the road on which Miss Grimstone was waiting with the buggy. We were in the hollow of the swamp and to our left the almost invisible path wound until it reached the higher ground on which stood D'Eath Farm.
Pons led the way, stepping meticulously along a path that was quite invisible to me. All around us in the icy night was the presence of the swamp; I was uneasily aware of it as though it were some living, sinister presence in the darkness, just waiting for a false step to drag us down into the bottomless depths. Pons' iron nerves seemed to armor him against such treacherous thoughts and I fingered the chill surface of my revolver, taking solid comfort from its reassuring metal.
The beams of light were momentarily invisible to us due to a rise in the ground and I realized that we were coming out on to the firmer terrain which led to the abandoned farm buildings. As we started uphill I was suddenly brought to a halt by an anguished cry against the silence of the night. It was repeated three times, each time more urgently and there was such fear in it that I felt the hairs on the nape of my neck rising; my flesh crawled.
Solar Pons gave an exclamation of anger and seized my arm.
"He is more clever than I thought, Parker! If I do not mistake the situation he is coming from the roadside and not from the farm. There is not a moment to lose!"
I tucked my arms into my sides and ran until my lungs were bursting but Pons was fleeter, covering the uphill path at a tremendous rate. As we climbed we were able to see the drama that was being played out on the rough upland track leading to the abandoned farm.
To my relief Silas Grimstone appeared to be unharmed, for we could see his light bobbing not more than a hundred yards in front of us. Behind him, moving at an alarming speed was an horrific apparition I cannot forget. Bluish yellow, seen first as a halo of crawling flame, then as a hard-edged figure, it appeared to float erratically.
The figure was indeterminately tall, surmounted by a hideous face lapped in baleful fire that changed shape as we watched. It was gaining on Grimstone with every second and with a last terrified look over his shoulder the old man at last saw us coming to the rescue, for his torch altered course as our paths closed.
"For God's sake save me, Mr. Pons!" he croaked with the last of his breath before sinking down exhausted on to the path about fifty paces away.
"Parker—" Pons ordered coolly, "two rounds and aim high, if you please."
The phantom blue figure was still coming in short hopping motions. The thing could not have seen us running against the dark background of bushes but as it was now alarmingly close to the fallen figure of the old man, I fired two shots into the air. The flash of flame and the detonation of the explosions seemed incredibly loud. I was momentarily blinded but when I opened my eyes again the marsh was empty; that blue, writhing figure might never have existed.
"Good heavens, Pons!" I cried. "The thing has disappeared."
"Never mind that," said Solar Pons crisply. "Let us just make sure that no harm has come to old Grimstone."
We hurried over the short stretch of ground that separated us from our client and found him lying exhausted, winded but recovering. I put down my revolver on a nearby stump and examined him by the light of his own torch.
"He is all right, Pons," I said, feeling his irregular pulse. "Just a fright."
"It might have meant my death!" the old man snarled with astonishing vindictiveness. I helped him up.
"We had better get him back to the manor, Pons."
Solar Pons put up his hand. There was irritation on his face. "There will be time enough for that later, Parker. Just douse the light. The game is far from over yet."
His rigid attitude and rapt attention to the matter in hand affected even Grimstone for he stopped his mumbling and went to stand quietly by the stump. Pons had sunk to his knees and now that I had switched off the torch, was almost invisible in the darkness. He moved forward, urging me to follow and I kept close to him, leaving Grimstone behind. I had not gone ten yards before I realized I had forgotten the revolver, but subsequent events happened so quickly that it became immaterial.
Pons put his hand on my arm as I came to a halt beside him. He bent down beside the path: there was just enough light to see that he was groping about on the ground. He gave a grunt as he found what he wanted — a loose stone which was frost-bond to the earth. He prised it loose and rose to his feet.
He threw it outward into the swamp; we waited a few seconds with straining ears. The sudden sharp crack of breaking ice and then the loud splash which followed sounded thunderous in the silence. At the same moment there was a loud rustling of branches and the same ghastly blue phantom figure reappeared not thirty feet in front of us.
"Come on, Parker!" Pons yelled. "My theory was correct."
There were blundering noises ahead as I followed Pons, all fear forgotten in the sudden conviction that we had to deal with a mortal being and not some actual phantom of the marsh. Ahead of us the bluish figure ducked and twisted with incredible agility, now appearing and then suddenly disappearing. The outline was curiously elongated and narrow and sometimes the blackness of night intervened for seconds at a time as the thing fled before us.
I stumbled on a root and Pons slackened a moment, turning back toward me. We were among the farm buildings now and with the respite afforded, the apparition had again disappeared.
"What was it, Pons?" I asked breathlessly.
Solar Pons chuckled with satisfaction.
"It is mortal enough I fancy, Parker," he said. "There is no time to explain now. We shall find the answer to our problems at D'Eath Farm unless my reasoning is very wide of the mark."
We were close by the buildings and crept cautiously along in their shadow. Pons stopped once or twice and listened intently. He tried the door of one of the sheds. It opened quietly to his touch. He put his lips against my ear.
"As I thought, Parker. This has been used as the phantom's changing room."
"He is not here now?"
"We shall see."
Abruptly and without any attempt at silence he flung open the door. At the same moment a strong beam of light from his flashlight stabbed out across the room. The place appeared empty. It was simply a brick and wood shell, with an oil lamp hanging from a dusty beam. It was a somber place, of shadow and darkness. In the center were two wooden boxes; on the top of one a tin was standing, together with a mirror and some brushes.
Solar Pons chuckled. Once again I caught the acrid chemical flavor. He tentatively tested the material in the tin with his fingertip, held it against his face, sniffing deeply.
"A solution of phosphorus, Parker! As I suspected from the beginning. There is your phantom."
"That is all very well, Pons," said I. "But how can he disappear in such a manner?"
"We shall find out in a moment or two," he said calmly, his sharp eyes assayed the room.
Then he did an astonishing thing. He stooped and quickly picked up the smaller of the two boxes, which had evidently served as a seat. He hurled it into the darkest corner of the shed. There was a sudden howl of pain, as Pons flung himself onto a vague shadow which stirred from the wall; there was a brief scuffle that knocked the light to the ground.