“Anything fresh about the Riversbrook case?” he asked.

“No; nothing fresh,” replied Inspector Chippenfield, looking Crewe straight in the face.

“You are a long time in making an arrest,” said Crewe, in a bantering tone.

“We want to arrest the right man,” was the reply.  “There’s nothing like getting the right man to start with; it saves such a lot of time and trouble.  Where are you off to?”

“I’m taking a run down to Scotland.”

The inspector glanced at Crewe rather enviously.

“You are fortunate in being able to enjoy yourself just now,” he said meaningly.

“I won’t drop work altogether,” remarked Crewe.  “I’ll make a few inquiries there.”

“About the Riversbrook affair?”

“Yes.”

With the murderer practically arrested, Inspector Chippenfield permitted himself the luxury of smiling at the way in which Crewe was following up a false scent.

“I thought the murder was committed in London—­not in Scotland,” he said.

“Wrong, Chippenfield,” said Crewe, with a smile.  “Sir Horace was murdered in Scotland and his body was brought up to London by train and placed in his own house in order to mislead the police.  Good-bye.”

As the taxi-cab drove off, Inspector Chippenfield turned to his subordinate and said, “We’ll rub it into him when he comes back and finds that we have got our man under lock and key.  He’s on some wild-goose chase.  Scotland!  He might as well go to Siberia while’s he’s about it.”

With a warrant in his pocket Inspector Chippenfield, accompanied by Rolfe, set out for Macauley Mansions, Westminster.  They found the Mansions to be situated in a quiet and superior part of Westminster, not far from Victoria Station, and consisting of a large block of flats overlooking a square—­a pocket-handkerchief patch of green which was supposed to serve as breathing-space for the flats which surrounded it.

Macauley Mansions had no lift, and Number 43, the scene of the events of Hill’s confession, was on the top floor.  Inspector Chippenfield and Rolfe mounted the stairs steadily, and finally found themselves standing on a neat cocoanut door-mat outside the door of No. 43.  The door was closed.

“Well, well,” said the inspector, as he paused, panting, on the door-mat and rang the bell.  “Snug quarters these—­very snug.  Strange that these sort of women never know enough to run straight when they are well off.”

The door opened, and a young woman confronted them.  She was hardly more than a girl, pretty and refined-looking, with large dark eyes, a pathetic drooping mouth, and a wistful expression.  She wore a well-made indoor dress of soft satin, without ornaments, and her luxuriant dark hair was simply and becomingly coiled at the back of her head.  She held a book in her left hand, with one finger between the leaves, as though the summons to the door had interrupted her reading, and glanced inquiringly at the visitors, waiting for them to intimate their business.  She was so different from the type of girl they had expected to see that Inspector Chippenfield had some difficulty in announcing it.