M. Fauvel made it a rule never to keep any large sums of money on the premises, but to deposit all such amounts in the keeping of the Bank of France. As this sum, however, had to be paid the first thing in the morning, the chief cashier, M. Prosper Bertomy, thought he was justified in obtaining the amount from the Bank of France on the evening of the 27th, and in locking it up in the bank safe against the morning.
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 £12,000 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 £12,000 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.
Investigation of the case was at first entrusted to a detective named Fanferlot, nicknamed by his comrades the "Squirrel." Fanferlot's examination of the premises resulted in little. All he discovered was a scratch upon the door of the safe, but certain words that passed between M. Fauvel and his niece, which seemed to indicate that the former was secretly opposed to the marriage of Madeline with Bertomy, caused him to jump to the conclusion that the banker had robbed his own safe in order to bring disgrace upon his cashier. He connived, however, at the arrest of Bertomy, hoping that later on he might obtain great kudos for himself by unmasking the banker. What might have been the result of his improper and unofficial methods will never be known, but in all probability great inconvenience would have been caused to a number of innocent persons and the whole course of justice thwarted had it not been for the intervention of the great and famous M. Lecoq.
M. Lecoq's interest in the bank robbery case was largely a personal one. Even detectives have hearts, and M. Lecoq had loved with heart and soul a charming young girl named Nina Gipsy. Under the name of Caldas in one of his innumerable disguises, he had wooed her for many months. When he thought at last that he had won her affections, she had fled to the protection of no less a person than Prosper Bertomy himself. The cashier cared nothing for her, but embittered by an estrangement that had sprung up between Madeline and himself, he had sought forgetfulness in her society. Bertomy's arrest gave Lecoq an opportunity for a noble revenge. He determined to prove to the woman he loved his superiority over his rival by saving the cashier from disgrace.
Though the case looked black against Bertomy, for it was shown that he was heavily in debt, and living far beyond his means, Lecoq was satisfied that he had not committed the crime. When Fanferlot, hopelessly befogged, called for his advice at his house in the Rue Montmartre, the great detective deigned to explain the preliminary data and the deductions from the data he had made.