At the same moment, even as he felt the sudden shock as the submarine paused abruptly in her pace, he sprang from his seat and turned toward the door, ready for anything with one hand on his automatic, for he felt sure that he was in danger.
In the darkness behind he could see nothing, but the slight squeaking of a board gave evidence of another presence. Frank, with the searchlight behind, was in full view of the other, and the lad realized it.
With a quick backward leap he snapped off the searchlight, and then dropped quickly to the floor, even as a figure rushed toward him in the darkness.
Frank’s ruse undoubtedly stood him to good advantage. A foot struck his prostrate body, and the figure of a man pitched over him, muttering a fierce imprecation as he fell to the floor.
Before the latter could rise, Frank grappled with him. Quickly reversing his revolver, he brought the butt of the weapon down in the direction in which he judged the man’s head to be. It struck something soft, and a guttural howl of pain went up.
“A spy!” Frank found time to think to himself.
But he had not struck the man’s head, only a hand which had been outstretched, and before he could draw his pocket searchlight to ascertain what damage he had done, the lad felt a pair of arms about his neck, and a hand seeking to entwine itself in his throat.
His revolver he found now to be of no use, so he dropped it and struck out blindly with his bare fists. Once, twice, his fists found their mark, and each time a blow went home the lad was rewarded by hearing cries of pain from his opponent.
As the two struggled, there flashed before the lad a vision of a man running from where the D-16 lay in drydock some days before.
“I guess we have got him at last,” the lad muttered between his teeth, and putting all his force behind one more blow, he struck out savagely.