"What kind of call?"
The man, whom the uncanny happening clearly had frightened, seemed puzzled for a suitable description.
"A sort of wail, sir," he said at last. "I never heard anything like it before, and don't want to again."
"Like this?" inquired Smith, and he uttered a low, wailing cry, impossible to describe. Wills perceptibly shuddered; and, indeed, it was an eerie sound.
"The same, sir, I think," he said, "but much louder."
"That will do," said Smith, and I thought I detected a note of triumph in his voice. "But stay! Take us through to the back of the house."
The man bowed and led the way, so that shortly we found ourselves in a small, paved courtyard. It was a perfect summer's night, and the deep blue vault above was jeweled with myriads of starry points. How impossible it seemed to reconcile that vast, eternal calm with the hideous passions and fiendish agencies which that night had loosed a soul upon the infinite.
"Up yonder are the study windows, sir. Over that wall on your left is the back lane from which the cry came, and beyond is Regent's Park."
"Are the study windows visible from there?"
"Oh, yes, sir."