The man shook his head.
"If I were a vulgar burglar I might assist you," he said, "but my branch of the profession does not take me to the suburbs."
"We will get a Kingston Directory and go through it," said McNorton; "we have one on the file at Scotland Yard. If——"
Beale suddenly raised his hand to enjoin silence: he had heard a familiar step in the corridor outside.
"That's van Heerden," he said in a low voice, "he has been out all the morning."
"Has he been shadowed?" asked McNorton in the same tone.
"My man lost him," he said.
He tiptoed along the passage and stood listening behind the door. Presently he heard the doctor's door close and came back.
"I have had the best sleuth in America trailing him," he said, "and he has slipped him every time."