Two men were crossing the street, heading directly for the shop door.  The arc lamp lighted up their faces.  It was inspector Lannigan of headquarters and Whitey Mack!  The quick intake of Jimmie Dale breath was sucked through clenched teeth.  They were close on his heels then—­far closer than he had imagined.  It would take Whitey Mack scarcely any longer to open that front door than it had taken him.  Close on his heels!  His face was rigid.  He could hear them now at the door.  The flashlight in his hand winked down the length of the room.  If was a dangerous thing to do, but it was still more dangerous to stumble into some object and make a noise.  He darted forward, circuiting a workbench, a stool, a small hand forge.  Again the flashlight gleamed.  Against the side wall, near the rear, was another workbench, with a sort of coarse canvas curtain hanging part way down in front of it, evidently to protect such things as might be stored away beneath it from dust, and Jimmie Dale sprang for it, whipped back the canvas, and crawled underneath.  He was not an instant too soon.  As the canvas fell back into place, the shop door opened, closed, and the two men had stepped inside.

Whitey Mack’s voice, in a low whisper though it was, seemed to echo raucously through the shop.

“Mabbe we’ll have a sweet wait, but I got the straight dope on this.  He’s going to make a try for Dutchy’s sparklers to-night.  We’ll let him go the limit, and we don’t either of us make a move till he’s pinched them, and then we get him with the goods on him.  He can’t get away; he hasn’t a hope!  There’s only two ways of getting in here or getting out—­this door and window here, and a window that’s down there at the back.  You guard this, and I’ll take care of the other end.  Savvy?”

“Right!” Lannigan answered grimly.  “Go ahead!”

There was the sound of footsteps moving forward, then a vicious bump, the scraping of some object along the floor, and a muffled curse from Whitey Mack.

“Use your flashlight!” advised the inspector, in a guarded voice.

“I haven’t got one, damn it!”, growled Whitey Mack.  “It’s all right.  I’ll get along.”

Again the steps, but more warily now, as though the man were cautiously feeling ahead of him for possible obstacles.  Jimmie Dale for a moment held his breath.  He could have reached out and touched the man as the other passed.  Whitey Mack went on until he had taken up a position against the rear wall.  Jimmie Dale heard him as he brushed against it.

Then silence fell.  He was between them now.  Stretched full length on the floor, Jimmie Dale raised the lower portion of the canvas away from in front of his face.  He could see nothing; the place was in Stygian blackness; but it had been close and stifling, and, at least, it gave him more air.

The minutes dragged by—­each more interminable than the one that had gone before.  Not a movement, not a sound, and then, through the stillness, very faint at first, came the regular, repressed breathing of Whitey Mack, who was much the nearer of the two men.  And, once noticeable, almost imperceptible as it was it seemed to pervade the room and fill it with a strange, ominous resonance that rose and fell until the blackness palpitated with it.