"So it is!" Miriam's excitement was rising. "The words we have so far are, 'watch thirteenth letter----grave.'" "Now for the last stamp!" Trenholm took up gauge and pencil. "The odd letters are E, two I's, one indicated by another pinhole, and S. The even letters are C, D, S, U. The position of the stamp shows that the first letter is S. Of the four even letters available for the next position, only the vowel can be used, making Su." Trenholm paused and wrote rapidly several combinations of the available letters, then looked up with a low exclamation--"Suicides." "And the completed message then stands--'Watch thirteenth letter suicides grave,'" repeated Miriam. "What do you make of it, Mr. Trenholm?" "Nothing--now," he admitted frankly. "We know the code. Help me decipher these other eleven envelopes and the burnt one. Fortunately the stamps on it are intact." Half an hour later Miriam and Trenholm sat back in their chairs and looked at each other. The latter took up one of the pads they had used. "Here are the thirteen decoded messages, of five words each, concealed in the stamps on the thirteen envelopes," he stated. "Listen carefully, Miss Ward, and tell me what you make of them." Fear Paul suspicious of Betty. Unwise to trust her judgment. Judge her influence is waning. Is there any other woman? Last interview with Paul disastrous. He declines to return jewel. Do not lose your nerve. Believe he can prove nothing. Does not guess your motive. Situation growing tense; money required. Learned hiding place changed often. Next time can tell definitely. Watch thirteenth letter; suicides grave. Miriam wrinkled her forehead in deep thought. "For whom were those messages intended, Mr. Trenholm?" she asked. "For the man who later killed Paul Abbott," he replied quietly. "And he--" "Is some one who was with Paul and had access to his mail, and so could read the code on these apparently innocent letters." Trenholm rose suddenly and looked down at her. "It was a devilish scheme and devilishly carried out." "By Boris Zybinn's confederate." Miriam also rose. "Have you any idea who that confederate is?" Absently Trenholm took up his pipe and fingered it. "Some one who knew Paul intimately," he said. "And who has been with him during the past few months, for the dates on these letters cover that period of time. But as to his identity--the coded messages give no clue." "That is true," agreed Miriam. "Another question--When he murdered Paul Abbott did he secure the Paltoff diamond?" Trenholm had located his tobacco pouch and filled his pipe mechanically, his thoughts elsewhere. "Frankly," he said slowly, "I am inclined to think he didn't." CHAPTER XVII CHERCHEZ LA FEMME