“And there was nothing suspicious—­you saw no one?”

“I saw Mr. Roberts and his lady coming home from the theatre.  But he lives at the other end of Tanton Gardens.  And I saw the housemaid at Mr. Fielding’s come out to the pillar-box.  That was a few minutes after eleven.  I didn’t see anybody at all the second time.”

“Nobody at the judge’s place—­no taxi, or anything like that?”

“No, sir.”

The taxi-cab turned swiftly into the shady avenue of Tanton Gardens, where Sir Horace Fewbanks lived, and in a few moments pulled up outside of Riversbrook.  The house stood a long way back from the road in its own grounds.  Inspector Seldon and Flack passed rapidly through the grounds and reached the front door of the mansion.  There was nobody about; the place seemed deserted, and the blinds were down on the ground-floor windows.  Inspector Seldon knocked loudly at the front door with the big, old-fashioned brass knocker, and rang the bell.  He listened intently for a response, but no sound followed except the sharp note of the electric bell as Flack rang it again while Inspector Seldon bent down with his ear at the keyhole.  Then the inspector stepped back and regarded the house keenly for a moment or two.

“Put your finger on that bell and keep on ringing it, Flack,” he said suddenly.  “I see that some of the blinds are down, but there’s one on the first floor which is partly up.  It looks as though the house had been shut up and somebody had come back unexpectedly.”

“Perhaps it’s Hill, the butler,” said Flack.

“If he’s inside he ought to answer the bell.  But keep on ringing while I knock again.”

The heavy brass knocker again reverberated on the thick oak door, and Inspector Seldon placed his ear against the keyhole to ascertain if any sound was to be heard.

“Take your finger off that bell, Flack,” he commanded.  “I cannot hear whether anybody is coming or not.”  He remained in a listening attitude for half a minute and then plied the knocker again.  Again he listened for footsteps within the house.  “Ring again, Flack.  Keep on ringing while I go round the house to see if there is any way I can get in.  I may have to break a window.  Don’t move from here.”

Inspector Seldon went quickly round the side of the house, trying the windows as he went.  Towards the rear of the house, on the west side, he came across a curious abutment of masonry jutting out squarely from the wall.  On the other side of this abutment, which gave the house something of an unfinished appearance, were three French windows close together.  The blinds of these windows were closely drawn, but the inspector’s keen eye detected that one of the catches had been broken, and there were marks of some instrument on the outside woodwork.

“This looks like business,” he muttered.