"That will help you," cried Sheila eagerly. "I hope so. It is, as I said, a paper of peculiar texture, and doubtless many tons of it have been sold. If, as I guess, it is now off the market, I shall be compelled to fix a date. If I do that, it would considerably narrow the field of my inquiries." After a little further conversation, Smeaton took his leave with the letter in his possession. Sheila and Wingate, when they were alone, indulged in mutual admiration of his powers of analysis and deduction. The detective, an hour later, looked in upon Mr Newsom-Perry, with whom he was slightly acquainted, and handed him the document. "We found this amongst the papers you sent to Miss Monkton," he explained. "I called on the chance of finding that your client had spoken to you, at one time or another, of some man who sent him a threatening letter. I may say that we have found no allusion to it amongst the other papers." "Which seems to show that Monkton did not attach any importance to it himself, I should say," remarked the solicitor. "No, so far as I am concerned he never alluded to the matter. You attach some importance to it--eh?" "Some," replied Smeaton guardedly. "Of course, you have a wider experience of these things than I, and you are wise to neglect no possible clue. Still, I should think that any big counsel in extensive practice has many letters of this kind from impulsive and angry litigants, who regard him as the author of their ruin." Smeaton rose. "It may be so," he said quietly. "This man was angry, but he was not impulsive; the handwriting alone proves that. He wrote the letter at white heat, but he is of a resolute and determined character." Even though the writer of the anonymous threat had overlooked the fact that a watermark was on the paper, the latter point was not half so easy to clear up as Sheila and Wingate expected. To the chief firms of paper makers and paper agents in the City Smeaton, through the following days, showed a tracing of the watermark, but without result. Nobody could identify it. The managing director of one firm of paper agents in Queen Victoria Street declared it to be a foreign paper, even though it was marked "Westford Mill." "The vogue for English notepaper on the Continent has led French and German mills to produce so-called `English writing paper'," he added. "And if I am not mistaken this is a specimen." For nearly a week Smeaton prosecuted his inquiries of stationers, wholesale and retail, in all parts of the metropolis, taking with him always the tracing of the watermark. He did not carry the letter, for obvious reasons. One day at a small retail stationer's in the Tottenham Court Road, when he showed the tracing to the elderly shopkeeper, the man exclaimed: