The figure had appeared about twenty yards ahead of him and then it was gone.

Robert was filled with fierce anger that the man should show such brazen effrontery, and impulsively he pursued.

Profiting by his experience with the spy, he now had a pistol in his pocket, and clutching the butt of it he hurried after the elusive shadow.
He caught a second glimpse.

It was surely Garay, and he was running along the shore, up the stream.
Robert's anger rose by leaps.

The spy's presumption was beyond all endurance, but he would make him pay for it this time.