In Secret by Robert W Chambers The case in question concerned a letter in a yellow envelope, which was dumped along with other incoming mail upon one of the many long tables where hundreds of women and scores of men sat opening and reading thousands of letters for the Bureau of P. C.-whatever that may mean. In due course of routine a girl picked up and slit open the yellow envelope, studied the enclosed letter for a few moments, returned it to its envelope, wrote a few words on a slip of paper, attached the slip to the yellow envelope, and passed it along to the D. A. C.-whoever he or she may be. The D. A. C., in course of time, opened this letter for the second time, inspected it, returned it to the envelope, added a memorandum, and sent it on up to the A. C.-whatever A. C. may signify. Seated at his desk, the A. C. perused the memoranda, glanced over the letter and the attached memoranda, added his terse comment to the other slips, pinned them to the envelope, and routed it through certain channels which ultimately carried the letter into a room where six silent and preoccupied people sat busy at six separate tables. Fate had taken charge of that yellow envelope from the moment it was mailed in Mexico; Chance now laid it on a yellow oak table before a yellow-haired girl; Destiny squinted over her shoulder as she drew the letter from its triply violated envelope and spread it out on the table before her. A rich, warm flush mounted to her cheeks as she examined the document. Her chance to distinguish herself had arrived at last. She divined it instantly. She did not doubt it. She was a remarkable girl. The room remained very still. The five other cipher experts of the P. I. Service were huddled over their tables, pencil in hand, absorbed in their several ungodly complications and laborious calculations. But they possessed no Rosetta Stone to aid them in deciphering hieroglyphics; toad-like, they carried the precious stone in their heads, M. D. No indiscreet sound interrupted their mental gymnastics, save only the stealthy scrape of a pen, the subdued rustle of writing paper, the flutter of a code-book's leaves thumbed furtively. The yellow-haired girl presently rose from her chair, carrying in her hand the yellow letter and its yellow envelope with yellow slips attached; and this harmonious combination of colour passed noiselessly into a smaller adjoining office, where a solemn young man sat biting an unlighted cigar and gazing with preternatural sagacity at nothing at all.