"Remember," I said, "your theory means another man up there, and you haven't yet--" "Please, Mr. Boyne, don't take two and two and make five of them at this stage of the game," she checked me hastily, and I left them together while I made a hurried survey of the hall ceilings, looking for the scuttle. There was no hatchway in view, so I started down to the clerk to make inquiry. As I passed Clayte's open door, Miss Wallace seemed to be adjusting her turban before the dresser mirror, while Worth waited impatiently. "Just a minute," I called. "I'll be right back," and I ducked into the elevator. CHAPTER VI ON THE ROOF When I returned with a key and the information that the way to the roof ran through the janitor's tool-room at the far end of the hall, I found my young people already out there. Worth was trying the tool-room door. "Got the key?" he called. "It's locked." "Yes." I took my time fitting and turning it. "How did you know this was the room?" "I didn't," briefly. "Bobs walked out here, and I followed her. She said we'd want into this one." She'd guessed right again! I wheeled on her, ejaculating, "For the love of Mike! Tell a mere man how you deduced this stairway. Feminine intuition, I suppose." I hadn't meant to be offensive with that last, but her firm little chin was in the air as she countered, "Is it a stairway? It might be a ladder, you know." It was a ladder, an iron ladder, as I found when I ushered them in. My eyes snapped inquiry at her. "Very simple," she said. Worth was pushing aside pails and boxes to make a better way for her to the ladder's foot. "There wouldn't be a roof scuttle in the rented rooms, so I knew when you called in to tell us there was none in the halls." "I didn't. I said nothing of the sort." Where was the girl's fine memory that she couldn't recollect a man's words for the little time I'd been gone! "All I said was, 'Just a minute and I'll be back.'" "Yes, that's all you said to Worth." She glanced at the boy serenely as he waited for her at the ladder's foot. "He's not a trained observer; he doesn't deduce even from what he does observe." There were twinkling lights in her black eyes. "But what your hurried trip to the office said to me was that you'd gone for the key of the room that led to the roof scuttle." Well, that was reasonable--simple enough, too; but, "This room? How did you find it?" She stepped to the open door and placed the tip of a gloved finger on the nickeled naught that marked the panels. "The significant zero again, Mr. Boyne," she laughed. "Here it means the room is not a tenanted one, and is therefore the way to the roof. Shall we go there?" "Well, young lady," I said as I led her along the trail Worth had cleared, "it must be almost as bad to see everything that way--in minute detail--as to be blind." "Carry on!" Worth called from the top of the ladder, reaching down to aid the girl. She laughed back at me as she started the short climb.