That night, while walking home, the idea occurred to Rolfe of going over to Camden Town after supper to see if by questioning Hill again he could throw a little more light on what had taken place at Doris Tanning’s flat the night Sir Horace Fewbanks was murdered.  Hill had been questioned and cross-questioned at Scotland Yard by Inspector Chippenfield concerning the events of that night, and professed to have confessed to everything that had happened, but Rolfe thought it possible he might be able to extract something more which might assist in strengthening what Crewe regarded as the weak points in the police case against Birchill.  Rolfe had every justification for such a visit, for, though Hill had not been arrested, he had been ordered by Inspector Chippenfield to report himself daily to the Camden Town Police Station, and the police of that district had been instructed to keep a strict eye on his movements.  Inspector Chippenfield did not regard his principal witness in the forthcoming murder trial as the sort of man likely to bolt, but if he permitted him for politic reasons to retain his liberty, he took every precaution to ensure that Hill should not abuse his privilege.

Rolfe lived in lodgings at King’s Cross, and, as the evening was fine and he was fond of exercise, he decided to walk across to Hill’s place.

As he walked along his thoughts revolved round the murder of Sir Horace Fewbanks, and the baffling perplexities which had surrounded its elucidation.  Had they got hold of the right man—­the real murderer—­in Fred Birchill?  Rolfe kept asking himself that question again and again.  A few hours ago he had not the slightest doubt on the point; he had looked upon the great murder case as satisfactorily solved, and he had thought with increasing satisfaction of his own share in bringing the murderer to justice.  He had anticipated newspaper praise on his sharpness:  judicial commendation, a favourable official entry in the departmental records of Scotland Yard, with perhaps promotion for the good work he had accomplished in this celebrated case.  These rosy visions had been temporarily dissipated by the conversation he had had with Crewe that morning.  If Crewe had not succeeded in destroying Rolfe’s conviction that the murderer of Sir Horace Fewbanks had been caught, he had pointed out sufficient flaws in the police case to shake Rolfe’s previous assurance of the legal conviction of Birchill for the crime.  The way in which Crewe had pulled the police case to pieces had shown Rolfe that the conviction of Birchill was by no means a foregone conclusion, and had left him a prey to doubts and anxiety which Inspector Chippenfield’s subsequent depreciation of the detective’s views had not altogether removed.

The little shop kept by the Hills was empty when Rolfe entered it, but Mrs. Hill appeared from the inner room in answer to his knock.  The faded little woman did not recognise the police officer at first, but when he spoke she looked into his face with a start.  She timidly said, in reply to his inquiry for her husband, that he had just “stepped out” down the street.