Cool air rose from the river, driving before it long, grey streamers of mist. Up through the trees it spread, close to the ground, dense as smoke. Across the sandbar, well up on the bank above, in the deep shadow of the balsam, a bright fire etched in bold relief the faces of Corporal Rand and the three boys. They made a complete circle around the fire and were conversing eagerly. Just now it was Sandy who held the center of interest.

“Something underhanded going on at Half Way House,” he explained to the corporal. “I think that Uncle Walter is suspicious of Factor Frazer. I don’t know exactly what the trouble is, but I think it has something to do with the way Mr. Frazer has been keeping his accounts. You see, Uncle Walter is Chief Factor for this district and audits the books of all the trading posts. He acted very mysterious when he asked us to go over to Half Way House. Didn’t he, Dick?”

“Yes, he did,” Dick corroborated his chum.

“It looks to me,” Sandy went on, “as if Mr. Frazer suspected that we were spies sent by my uncle and took the method he did to get rid of us.”

“Seems very likely,” smiled the policeman.

“Wolf Brennan and Toby McCallum were at the post when we left,” continued Sandy. “After what has happened, we can draw only one conclusion, that these two men are paid emissaries of Frazer’s. I suspect he wants to keep us out here until he has had time to cover up some sort of deviltry.”

Corporal Rand rose and gazed down into the fire.

“It would seem so, Sandy. Something deeply mysterious afoot there. Probably another case for the police to solve. I’ve never known it to fail. No sooner do we hear of an important case and start working upon it, than something else crops up. We’ve done nothing but patrol duty until this Miller case came to our attention. I start out upon this case when I learn of this business at Half Way House. Probably before I get back from Caribou Lake, there will be a murder or two added to the growing list of crimes.”

“Do you plan to have us accompany you to Caribou Lake?” Dick asked.

“When I met you out here this afternoon, that was my intention. But now that I’ve talked with you and heard your story I’ve changed my mind. It’s more important that you should go on to Half Way House. By travelling as fast as you can, you should make it in four more days.”