The old Londoner had forgotten how few places there are at which one can stay in Sloane Street.
A bad twenty-four hours was in store for him.
They began well enough with the unexpected discovery that an eminent authority on crime and criminals, who had been a good friend to Langholm in his London days, was still in town.

The novelist went round to his house that night, chiefly because it was not ten minutes' walk from the Cadogan Hotel, and with little hope of finding anybody at home.

Yet there was his friend, with the midnight lamp just lighted, and so kind a welcome that Langholm confided in him on the spot.

And the man who knew all the detectives in London did not laugh at the latest recruit to their ranks; but smile he did.
"I'll tell you what I might do," he said at length.

"I might give you a card that should get you into the Black Museum at New Scotland Yard, where they would show you any relics they may have kept of the Minchin murder; only don't say why you want to see them.