She shot him a puzzled glance. "Yes?" she asked uncertainly.
"I was thinking of the night last fall when the two men were killed in their bunks. I heard a woman's voice inside that cabin—a woman talking over a telephone—" He threw up his head sharply. "You were there, Alison."
"I never went beyond the edge of the clearing," she declared, her lips setting defiantly. "You saw my tracks—"
"Yes," he interrupted with an impatient gesture. "That's what I'm getting at. Your tracks stopped twenty feet away from the cabin. Yet there was a woman inside, and if, as you insist, she wasn't you, then she had to be—"
Dexter caught his breath and swung around with kindling eyes to confront Colonel Devreaux. "It's a funny notion," he declared wonderingly, "and I can't quite make out why it never struck me before but—it's the only possible answer. This woman, whoever she was, never left the cabin.
"When I went out to look after my pony," he rushed on, "there were two people alive in the cabin. And when I reëntered the place there were two people dead. And there was no one else there at any time. The mysterious third person we've been looking for never existed."
"What are you driving at?" gasped the bewildered officer.
Dexter shook his head and turned again to Alison. "Did you know Mrs. Stark?" he asked tensely. "She's the only other woman I've heard of in this section of the forest. What was she like?
"Small woman, about thirty-five?" he inquired, as Alison stared blankly and failed to answer. "Thin, high-bridged nose, short black hair, black eyes, sallow complexion. Have I got her?"
The girl nodded without speaking.