"He's slipping," whispered Joe.
Frank glanced back again.
The stranger was indeed "slipping." His 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 her previous course. The abrupt, swerving motion finished the stranger.
With a groan, he slumped forward in his seat, and bowed his head on his arms.
Joe sprang up. With one bound he reached the man with the gun.
The stranger realized what was happening, and struggled to his feet. He raised the weapon, but Joe struck out and dashed the revolver from his hand. It described a flashing arc, then fell into the water with a splash.