The safe was a formidable-looking affair constructed entirely of wrought iron of treble thickness.  An ingenious device regulated its opening.  On the massive door were five movable steel buttons engraved with the letters of the alphabet.  Before the key could be inserted in the lock, these buttons had to be manipulated in the same order in which they had been used when the safe was last shut.  The buttons were arranged so that the letters on them formed some word, which was changed from time to time.  This word was known only to M. Fauvel and his cashier, each of whom possessed a key of the safe.

As soon as the bank opened on the morning of February 28, the count put in an appearance, and Prosper Bertomy went to the safe to obtain the money.  When, a second later, he reappeared, his face was ashy pale, and his steps tottered as he walked.  The L12,000 had disappeared from within the safe.  What made the affair all the more mysterious was that the safe was locked just as the cashier had left it the night before.

The room in which the safe was situated communicated with the bank by another room in which every night a tried servant of the establishment slept.  By a second door admittance was obtained to the private apartments of M. and Madame Fauvel and their niece Madeline.

As soon as M. Fauvel had heard the startling news, he first obtained the necessary money from the Bank of France, settled the business with the count, and then turned his attention to the elucidation of the robbery.  He summoned the cashier to his presence.

Bertomy was a young man of thirty to whom M. Fauvel had shown great kindness, advancing his interests wherever possible until, though very young for the position, he was his most important and most confidential employee.  Besides the paternal affection with which the bank manager regarded his cashier, another tie tended to make their relations all the stronger and more personal.  Bertomy loved M. Fauvel’s niece Madeline, and though a curious estrangement had sprung up between them during the previous nine or ten months, the banker always regarded their marriage as practically arranged.

The interview between the two men was a curious one.  To each it appeared that the other must be the thief.  They alone had the keys of the safe; they alone knew the magic word which could open the massive door.  The banker urged Bertomy to confess, promising him forgiveness; the other haughtily rejected the suggestion, and hinted that his employer had converted the L12,000 to his own use.  In the end M. Fauvel lost his temper, sent for the police, and before twenty-four hours were up, Prosper Bertomy, who but the day before had held one of the most important and envied positions in the financial world of Paris, was charged before a magistrate as being a common thief.