"No!" Yet I thought now that I could hear something. Vague footfalls. A rustling. And a microscopic whine, as though some device were within range of us.

Snap was fumbling in his pocket. "Wait! I've got a pair of low-scale detectors."

He put the little grids against his ears. I could hear the sharp intake of his breath. Then he seized me, pulled me down to the metal floor of the entryway.

"Back, Gregg! Get back!" I could barely hear his whisper. We crouched as far back into the doorway as we could get. I was armed. My official permit for the carrying of the pencil heat ray allowed me always to have it with me. I drew it now. But there was nothing to shoot at. I felt Snap clamping the grids on my ears. And now I heard something! An intensification of the vague footsteps I had thought I heard before.