“Third floor, von Hindenburg,” he rapped.  “Don’t argue.  Lead the way.”

For one dangerous moment the man’s brow lowered and his heavy face grew blackly menacing.  He exchanged a swift look with his friends seated at the disguised roulette table.  Kerry’s jaw muscles protruded enormously.

“Give me another answer like that,” he said in a tone of cold ferocity, “and I’ll kick you from here to Paradise.”

“No offense—­no offense,” muttered the man, quailing before the savagery of the formidable Chief Inspector.  “You come this way, please.  Some ladies call upon me this evening, and I do not want to frighten them.”

“No,” said Kerry, “you wouldn’t, naturally.”  He stood aside as a door at the further end of the room was opened.  “After you, my friend.  I said ‘lead the way.’”

They mounted to the third floor of the restaurant.  The room which they had just quitted was used as an auxiliary dining and supper-room before midnight, as Kerry knew.  After midnight the centre table was unmasked, and from thence onward to dawn, sometimes, was surrounded by roulette players.  The third floor he had never visited, but he had a shrewd idea that it was not entirely reserved for the private use of the proprietor.

A babel of voices died away as the two men walked into a room rather smaller than that below and furnished with little tables, cafe fashion.  At one end was a grand piano and a platform before which a velvet curtain was draped.  Some twenty people, men and women, were in the place, standing looking towards the entrance.  Most of the men and all the women but one were in evening dress; but despite this common armor of respectability, they did not all belong to respectable society.

Two of the women Kerry recognized as bearers of titles, and one was familiar to him as a screen-beauty.  The others were unclassifiable, but all were fashionably dressed with the exception of a masculine-looking lady who had apparently come straight off a golf course, and who later was proved to be a well-known advocate of woman’s rights.  The men all belonged to familiar types.  Some of them were Jews.

Kerry, his feet widely apart and his hands thrust in his overcoat pockets, stood staring at face after face and chewing slowly.  The proprietor glanced apologetically at his patrons and shrugged.  Silence fell upon the company.  Then: 

“I am a police officer,” said Kerry sharply.  “You will file out past me, and I want a card from each of you.  Those who have no cards will write name and address here.”

He drew a long envelope and a pencil from a pocket of his dinner jacket.  Laying the envelope and pencil on one of the little tables: 

“Quick march!” he snapped.  “You, sir!” shooting out his forefinger in the direction of a tall, fair young man, “step out!”

Glancing helplessly about him, the young man obeyed, and approaching Kerry: