Lugging his bag, he led the way with the air of one receiving rather than conferring a favour. "Curious how things fall out," he observed cheerfully; "isn't it?" "Yes--" "I mean, your popping up like this just when I was thinking of you. Coincidence, you know." "Coincidences," Sally informed him consciously, "are caviar only to book critics. There's nothing more common in real life." He suffered this instruction with a mildly anguished smile. "That's true, I presume, if one knows anything about real life. I don't go in for realistic novels you see, so can't say. But you're right one way: it isn't anything extraordinary, come to consider it, that you and I, both headed for Boston, should run into each other here. By the way," he added with a casual air, "speaking of coincidences, it sort of triple-plated this one to have your friend from Central Office hanging round so handy, didn't it? If he's in sight, why not be a sport and tip me off?" "I don't see the necessity," Sally returned, biting her lip--"yet." "Not from your point of view, perhaps--from mine, yes. Forewarned is fortunate, you know." "I dare say." "You won't put me wise?" "Certainly not." "Well, of course, one can guess why." "Can one?" "Why, forgive me for calling your bluff, it wouldn't be safe, would it? Of course, I'm a sure-enough bad man--and all that. But you must be a bird of my feather, or you wouldn't flock together so spontaneously." Sally opened her eyes wide and adopted a wondering drawl known to have been of great service to Miss Lucy Spode: "Why, whatever do you mean?" "Good!" Blue Serge applauded. "Now I _know_ where I stand. That baby stare is the high sign of our fraternity--of blackbirds. Only the guilty ever succeed in looking as transparently innocent. Too bad you didn't think of that in time." "I don't follow you," she said truthfully, beginning to feel that she wasn't figuring to great advantage in this passage of repartee. "I mean, your give-away is calculated to cramp your style; now you can't very well cramp mine, threatening to squeal." "Oh, can't I?" "No. I know you won't go through with it; not, that is, unless you're willing to face Sing Sing yourself. For that matter, I don't see how you're going to make Boston at all to-night, after that break, unless you go on your own; I don't believe I'm scared enough to stand for being shaken down for your transportation." He was gaining the whip-hand much too easily. She averted her face to mask a growing trepidation and muttered sullenly: "What makes you think I'm afraid--?" "Oh, come!" he chuckled. "I know you hadn't any lawful business in that house, don't I?" "How do you know it?" "Because if you had, I would now be going peaceful, with the kind policeman instead of being a willing victim of a very pleasant form of blackmail."