Without warning he suddenly bore down on the wheel and swung the motorboat about so that it was lying broadside to the waves.
"Here—what's the matter?" asked the stranger. "Where are you going now?"
"We're off our course. I'm heading in toward shore a little more so we can get out of the wind."
This explanation satisfied the stranger, although it became speedily apparent that the new course did not.
The Sleuth received the full force of the long rollers. The waves were not high enough to be dangerous, but the swells gave an undulating motion to the craft that swiftly increased the stranger's illness.
"He's slipping," whispered Joe.
Frank glanced back again.
The stranger was indeed "slipping." He teeth were tightly clenched. His face was almost green. His expression was that of a man who is deathly sick. But he still clung to the revolver and he still waved it feebly at the boys.
"Head her in toward Bayport," he demanded. "Do you want to make me sick?"
"This'll fix him," said Frank. "Get ready."
He bore down on the wheel again.
The Sleuth swung around at right angles to
