The boys talked the situation over at some length as they put away the films they had taken of the submarine attack, and agreed that "watchful waiting" was the best policy to adopt. As Blake had said, little could be gained by denouncing Labenstein with only the word of one witness to rely on.
"If all three of us catch him at his traitorous work, then we'll denounce him," suggested Blake.
"Yes, and the Frenchman, too!" added Charlie, in a louder voice, so that Blake raised a cautioning hand.
At that moment came a knock on their door, and a voice said:
"I am Mr. Labenstein!"
CHAPTER X
THE FLASHLIGHT
Almost like conspirators themselves, the boys looked at one another as the voice and knock sounded together. Blake was the first to recover himself.
"Come in!" he called, in as welcoming a tone as he could muster under the circumstances. Then as the knob of the door was ineffectually tried, he added: