There was only one entrance to the place, an exaggerated keyhole, to carry out the similitude of the safe-door alluded to.  The ground floor was occupied by the ordinary offices of the company; all the strong-rooms and safes lay in the steel-cased basement.  This was reached both by a lift and by a flight of steps.  In either case the visitor found before him a grille of massive proportions.  Behind its bars stood a formidable commissionaire who never left his post, his sole duty being to open and close the grille to arriving and departing clients.  Beyond this, a short passage led into the round central hall where Carrados was waiting.  From this part, other passages radiated off to the vaults and strong-rooms, each one barred from the hall by a grille scarcely less ponderous than the first one.  The doors of the various private rooms put at the disposal of the company’s clients, and that of the manager’s office, filled the wall-space between the radiating passages.  Everything was very quiet, everything looked very bright, and everything seemed hopelessly impregnable.

“But I wonder?” ran Carrados’s dubious reflection as he reached this point.

“Sorry to have kept you so long, my dear Max,” broke in Mr. Carlyle’s crisp voice.  He had emerged from his compartment and was crossing the hall, deed-box in hand.  “Another minute and I will be with you.”

Carrados smiled and nodded and resumed his former expression, which was merely that of an uninterested gentleman waiting patiently for another.  It is something of an attainment to watch closely without betraying undue curiosity, but others of the senses—­hearing and smelling, for instance—­can be keenly engaged while the observer possibly has the appearance of falling asleep.

“Now,” announced Mr. Carlyle, returning briskly to his friend’s chair, and drawing on his grey suede gloves.

“You are in no particular hurry?”

“No,” admitted the professional man, with the slowness of mild surprise.  “Not at all.  What do you propose?”

“It is very pleasant here,” replied Carrados tranquilly.  “Very cool and restful with this armoured steel between us and the dust and scurry of the hot July afternoon above.  I propose remaining here for a few minutes longer.”

“Certainly,” agreed Mr. Carlyle, taking the nearest chair and eyeing Carrados as though he had a shrewd suspicion of something more than met the ear.  “I believe some very interesting people rent safes here.  We may encounter a bishop, or a winning jockey, or even a musical comedy actress.  Unfortunately it seems to be rather a slack time.”

“Two men came down while you were in your cubicle,” remarked Carrados casually.  “The first took the lift.  I imagine that he was a middle-aged, rather portly man.  He carried a stick, wore a silk hat, and used spectacles for close sight.  The other came by the stairway.  I infer that he arrived at the top immediately after the lift had gone.  He ran down the steps, so that the two were admitted at the same time, but the second man, though the more active of the pair, hung back for a moment in the passage and the portly one was the first to go to his safe.”