I was just about to turn back when Rupert caught me by the elbow.
"Just listen to that," he said, and keeping my coat gripped in his right hand, he rapped with the knuckles of his left on the shutters of the basement window.

His air was so definite that I paused and even inclined my head for a moment towards it.

From inside was coming the murmur of an unmistakable human voice.
"Have you been talking to somebody inside ?" I asked suddenly, turning to Rupert.
"No, I haven't," he replied, with a grim smile, "but I should very much like to.

Do you know what somebody is saying in there ?" "No, of course not," I replied.
"Then I recommend you to listen," said Rupert sharply.
In the dead silence of the aristocratic street at evening, I stood a moment and listened.

From behind the wooden partition, in which there was a long lean crack, was coming a continuous and moaning sound which took the form of the words: "When shall I get out?
When shall I get out?
Will they ever let me out ?" or words to that effect.
"Do you know anything about this ?" I said, turning upon Rupert very abruptly.
"Perhaps you think I am the criminal," he said sardonically, "instead of being in some small sense the detective.