The stranger was no longer standing up; he was sitting back against the cushions again and he still held the revolver levelled at the Hardy boys, but there was a curious expression on his face, an expression of nausea; his eyes were staring and his face was pallid.
For a moment Frank could not understand what the matter was. Then, as the boat gave a lurch more violent than usual, he understood.
He nudged his brother.
"Getting seasick!" he whispered.
Joe glanced back, and when he saw that the stranger's florid face had changed in hue from a deep red to a greenish white he knew that the motion of the boat was indeed taking its effect. He forebore an impulse to chuckle at their passenger's plight.
"Give her a little more gas," ordered the stranger, in a curiously feeble voice. "You're not going fast enough."
He brandished the revolver threateningly.
Frank obligingly increased the speed of the Sleuth but the rocking motion only became more pronounced.
The stranger gulped, but he did not lower the weapon.
"That's better," he said, without enthusiasm.
"I'm going to give him something to be seasick about," whispered Frank.
