“Ah-ha, there you are—­the greater the confidence the greater the risk.  But only if your self-confidence results in carelessness.  Now do you know how this place is secured, Max?”

“I am told that they lock the door at night,” replied Carrados, with bland malice.

“And hide the key under the mat to be ready for the first arrival in the morning,” crowed Mr. Carlyle, in the same playful spirit.  “Dear old chap!  Well, let me tell you—­”

“That force is out of the question.  Quite so,” admitted his friend.

“That simplifies the argument.  Let us consider fraud.  There again the precautions are so rigid that many people pronounce the forms a nuisance.  I confess that I do not.  I regard them as a means of protecting my own property and I cheerfully sign my name and give my password, which the manager compares with his record-book before he releases the first lock of my safe.  The signature is burned before my eyes in a sort of crucible there, the password is of my own choosing and is written only in a book that no one but the manager ever sees, and my key is the sole one in existence.”

“No duplicate or master-key?”

“Neither.  If a key is lost it takes a skilful mechanic half-a-day to cut his way in.  Then you must remember that clients of a safe-deposit are not multitudinous.  All are known more or less by sight to the officials there, and a stranger would receive close attention.  Now, Max, by what combination of circumstances is a rogue to know my password, to be able to forge my signature, to possess himself of my key, and to resemble me personally?  And, finally, how is he possibly to determine beforehand whether there is anything in my safe to repay so elaborate a plant?” Mr. Carlyle concluded in triumph and was so carried away by the strength of his position that he drank off the contents of his second cup before he realized what he was doing.

“At the hotel I just spoke of,” replied Carrados, “there was an attendant whose one duty in case of alarm was to secure three iron doors.  On the night of the fire he had a bad attack of toothache and slipped away for just a quarter of an hour to have the thing out.  There was a most up-to-date system of automatic fire alarm; it had been tested only the day before and the electrician, finding some part not absolutely to his satisfaction, had taken it away and not had time to replace it.  The night watchman, it turned out, had received leave to present himself a couple of hours later on that particular night, and the hotel fireman, whose duties he took over, had missed being notified.  Lastly, there was a big riverside blaze at the same time and all the engines were down at the other end of the city.”

Mr. Carlyle committed himself to a dubious monosyllable.  Carrados leaned forward a little.

“All these circumstances formed a coincidence of pure chance.  Is it not conceivable, Louis, that an even more remarkable series might be brought about by design?”