"By the way, Trevisa," said the marshal, turning to the ex-secretary, "you must not let the princess's frown diminish your interest in the cipher letter found upon the spy Russakoff. Read me that riddle, and I will undertake to restore you to favor." "I fear my restoration will not come upon those terms," said Trevisa, lugubriously. "The cipher is a most baffling one. I should have a clue if you could name the writer." "How so?" "The first step in a problem of this sort is to know in what language the document is written; and of this I am ignorant. How, then, can I proceed? The principles of decipherment which an expert applies to one language fail when applied to another. But if I learn who the author is, and I discover that he knows, say, Russian only, the inference is that the document is written in that language; I apply certain principles deduced from a study of Russian, and the result is decipherment. The knowledge that the writer is versed in several languages would, of course, enhance the difficulty; but still, with time and patience success is certain. Have you no clue as to the writer?" Zabern was silent. He glanced at Paul as if wishing him away. "I will step aside for a moment," said Paul. "Not so," replied Trevisa. "Marshal, you can trust my friend Captain Woodville as surely as myself." "Then on my honor as a soldier I believe that the Duke of Bora was either the author or the recipient of that letter." "The duke!" cried Trevisa in amazement. "You accuse the duke of holding a treasonable correspondence with Russia? Impossible!" "Why impossible?" "Is it reasonable that he should seek to subvert the throne of a princess to whom he is affianced?" Zabern smiled cynically.