I've just understood everything, Weber.

You're a German and not a French spy, and you've played the traitor to Julie and Philip Lannes and me all along." There was enough moonlight for John to see that Weber's face was distorted by an evil smile.
"You've been a trifle slow in discovering just what I am," he said, calmly.

"I've wondered that a young man of your perception didn't find me out earlier." John flushed.

The Alsatian's effrontery, in truth, had been amazing and in that perhaps lay his success--so far.
"It's true," he said, "I should have suspected you sooner, but it did not occur to me that human nature could be so vile.

To undertake such risks and to use so much trickery and guile there must be a powerful motive, and in your case I can't guess it.