To the casual eye she was simply a weedy youth trudging towards his favourite pub. A moist and melancholy-looking cigarette dangled from the corner of her mouth; her face and hands were convincingly grimed; her shoulders slouched. The corduroy trousers were artistically torn, the ill-fitting coat dusty and clumsily patched, the tweed cap pulled down over her eyes in the approved rakish manner. There were only two things about her attire to distinguish her from the original of the part she was playing, and neither of these obtruded itself. One was her shoes--light black pumps with soles as thin and flexible as rubber wafers, which made no sound as they plodded lightly over the cobbles---the second was a little instrument of blued steel which nestled against her hip, for Susan Hawthorne had spent most of her unusual adolescence in those parts of the world where, the wise go heeled and the foolish are all dead. So Storm had decided that she wasn't to be in the Triangle picnic, had he? Well, he'd got another guess coming, she reflected grimly. Keep her out of it, when in her time she'd been through more hair-raising adventures, in company with old Smiler and Kit Arden, than she could remember in detail? Not much! She was swift on the uptake, was this slim girl. Storm had rambled on unsuspectingly about the mysterious warehouse in Billingsgate, and Uncle Joe had spoken sombrely of the mysterious Mr. Raegenssen. The faculty of adding two and two, and unfailingly producing a tentative dozen, was hers in a marked degree, and a few discreet investigations had done the rest. Oscar Raegenssen himself, that eccentric gentleman, was the worthy burgess who numbered that curious "saw-mill" among his goods and chattels, and the coincidence required closer scrutiny. There had remained only the minor problem of the escape from the watchful eye of Terry Mannering, and from the even more intent care of the plain-clothes watch-dog whom Storm had set over her.... To one of her breed, that difficulty was exceeding small. She chuckled reminiscently as she recalled the simple ruse she had employed to circumvent it. The Sud-Scandinavia Sawmill stood a little way back from the narrow street, occupying a whole block, and fronted by a wide stretch of pavement, not a hundred miles from Nicholson's Wharf--a gaunt sooty building from which by night and by day issued the muffled swoosh and clang of a tireless plant. A forbidden place--glancing up as she approached, she took in its massive dullness; the intangible air of secrecy; the barred and shuttered windows placed high up in the walls; the single narrow rat-hole-like entrance with its steel-mounted door. The demesne of Sud-Scandinavian Wood was going to be difficult.