“Brett,” Hewitt exclaimed with suddenness, “will you do me a favour? That woman understands Geldard’s secret comings and goings, as is plain from the letter. But she would appear to know nothing of where he is now, since she seems to have come here to find him. Perhaps this last absence of his has nothing to do with the others. In any case, will you follow this woman? She must be watched; but I want to see to the matter in other places. Will you do it?” Of course I assented at once. We had been descending the stairs as Hewitt spoke, keeping distance behind the girl we were following. “Thank you,” Hewitt now said. “Do it. If you find anything urgent to communicate, wire to me in care of the inspector at Crouch End Police Station. He knows me, and I will call there in case you may have sent. But if it’s after five this afternoon, wire also to my office. If you keep with her to Crouch End, where she lives, we shall probably meet.” We parted at the door of the office we were at first bound for, and I followed the girl southward. This new turn of affairs increased the puzzlement I already laboured under. Here was the girl Trennatt--who by all evidence appeared to be well acquainted with Geldard’s mysterious proceedings, and in consequence of whose letter, whatever it might mean, he would seem to have absented himself--herself apparently ignorant of his whereabouts, and even unconscious that he had left his office. I had at first begun to speculate on Geldard’s probable secret employment; I had heard of men keeping good establishments who, unknown to even their own wives, procured the wherewithal by begging or crossing-sweeping in London streets; I had heard also--knew, in fact, from Hewitt’s experience--of well-to-do suburban residents whose actual profession was burglary or coining. I had speculated on the possibility of Geldard’s secret being one of that kind. My mind had even reverted to the case, which I have related elsewhere, in which Hewitt frustrated a dynamite explosion by his timely discovery of a baker’s cart and a number of loaves, and I wondered whether or not Geldard was a member of some secret brotherhood of Anarchists or Fenians. But here, it would seem, were two distinct mysteries, one of Geldard’s generally unaccountable movements, and another of his disappearance, each mystery complicating the other. Again, what did that extraordinary note mean, with its crosses and its odd references to smoking? Had the dirty clay pipes anything to do with it? Or the half-smoked cigars? Perhaps the whole thing was merely ridiculously trivial after all. I could make nothing of it, however, and applied myself to my pursuit of Emma Trennatt, who mounted an omnibus at the Bank, on the roof of which I myself secured a seat. II Here I must leave my own proceedings to put in their proper place those of Martin Hewitt as I subsequently learnt them.