He waited a moment, listening. The silence was complete. Then he pushed the door open, looked into the empty room beyond, and led the way in.

They seemed to be in the center room of a three-room flat. An archway separated it from the room overlooking the street—a room faintly lighted by a glow through unwashed windows. A narrower open doorway separated it from the rear room.

Ken remembered the dim light that they had seen at the rear of the Tobacco Mart. He turned toward the rear room of the second-floor apartment.

“Easy,” he whispered. Sandy, behind him, needed no warning. He edged his feet forward as cautiously as if he were stalking a deer in the silent woods.

At the doorway that opened into the rear room they paused, a pair of silent shadows.

Suddenly Ken grabbed Sandy’s hand and pointed it at the thing he saw—a six-inch ragged round hole in the floor against one wall. Light came up through it, like a column of dim dust-filled smoke. And also, faintly through the opening, drifted the mumble of voices.

They were on the threshold of what must once have been a kitchen, Ken thought. And the hole in the floor had once given passage to a drain pipe.

Hardly daring to believe in their luck, he began to move carefully toward the upward-shining ray of light. Sandy edged along beside him.

They progressed scarcely an inch at a time, aware that they might be heard at any moment by the occupants of the room just under their feet. It took long minutes to cross the floor. But the voices below grew more distinct with every step they took. Before they reached their goal they had both identified the three voices taking part in the conversation below.

The boys had heard them all before. They were the voices of Barrack, Grace, and Cal.