“Bang again, Cunningham,” he ordered, “and go on banging until there’s some response. That’s the only way that we shall get anywhere. Whoever he is, he’s hiding himself away damned mysteriously. Still, I don’t want to break the door down if I can possibly avoid it. After all, the man may be innocent. This may not be the place we’re after, and we don’t want to make fools of ourselves to that extent, do we?”

Cunningham seized the door-knocker in a resolute grip, took a deep breath, and hammered away unmercifully for a full half-minute. Then he paused for breath, took a grip of the knocker once more, and prepared to make another fiendish din. It was not often that one had a chance, in the middle of a difficult case, to “let off steam” in this manner, and Cunningham was firmly resolved to make the most of the opportunity while it lasted. But it was not to last much longer. Before he had a chance to start again on his banging activities, Shelley stopped him with a wave of an imperious hand.

“I think he’s opening the window,” he said. And, as usual, Shelley was right.

The window of the room in the top story, the room the window-blind of which they had previously seen quivering, slowly opened. They looked up, wondering what the result might be. A head looked out, and a quavering voice enquired: “What’s all the row about down there?”

Shelley looked at the face that was disclosed to their view. At once he was compelled to admit that, unless this was the most brilliant of disguises, it could not be the man they were after.

The man who gazed down at them, his eyes screwed up in the difficult task of vision, was old, incredibly old. His face was a mass of wrinkles, and his beard was a dirty white. Shelley could not, from that distance below, see what the old man was clothed in, but what was visible appeared to be the collar of a very dirty old nightshirt.

Shelley cursed that he had not thought of asking Cartwright the colour of the old man’s beard. Then he might have been prepared for this shock. Still, better late than never, so he turned to Cartwright with a somewhat sheepish grin.

“That Mr. Ramsbottom?” he asked quietly.

“Ay,” answered Cartwright, and Shelley groaned. It looked as if they were on the wrong track after all, for certainly this old fogey was not the man they were after. Yet it was just barely possible that their enemy was hidden somewhere in the house, so they must make some sort of attempt to get in.

“We’re the police,” he shouted back. “Hunting an escaped prisoner.”

“Eh?” The old man appeared to be rather deaf.