That blot, he knew, had caused this sudden disappearance of a whole band of Shawnees, and he wanted to know more.

The black blot came down the stream and grew into shape and outline, and the shape and outline were those of a boat.

An Indian canoe?
No; it rapidly grew beyond the size of any canoe used by the savages, and began to stand up from the water in broad and stiff fashion.

Then Paul's heart thumped, because all at once he knew.

It was a flatboat, and it was certainly loaded with emigrants coming down the Ohio, women and children as well as men, and the Shawnees had laid an ambush.