La Touche regained the street and walked slowly back to his hotel. It was beginning to look very much as if the alibi could not be broken, and he was unable for the moment to see his next step in the matter. Nor had any information resulted from the labours of Mallet and Farol, the two men he had brought over to shadow Boirac. Up to the present the latter had been most circumspect, not having been anywhere or done anything in the slightest degree suspicious. As La Touche wrote a detailed report of his proceedings to Clifford, he felt for the first time a distinct doubt as to the outcome of his investigations. CHAPTER XXVI A CLUE AT LAST La Touche, having finished his report, put on his hat and sallied forth into the rue de la Fayette. He intended after posting his letter to cross to the south side and spend the evening with some friends. He was not in an agreeable frame of mind. The conclusion to which he was apparently being forced would be a disappointment to Clifford, and, if the theory of Boirac’s guilt broke down, he saw no better than the solicitor what defence remained. He sauntered slowly along the pavement, his mind brooding almost subconsciously on the case. Then, noticing a letter-box on the opposite side of the street, he turned to cross over. But as he stepped off the sidewalk an idea flashed into his mind and he stopped as if shot. That typewriter the pretty girl in Boirac’s office had been using was _a new machine_. La Touche was an observant man, and he had noted the fact, as he habitually noted small details about the objects he saw. But not until this moment did he realise the tremendously suggestive deduction which might be made from the fact. Lefarge, in his search for the machine on which the Le Gautier letter had been typed, had obtained samples from all the typewriters to which Boirac, so far as he could ascertain, had access. But what if that new machine replaced an old? What if that old machine had typed the Le Gautier letter and had been then got rid of so that samples taken by suspicious detective might be supplied from some other typewriter? Here was food for thought. If he could prove anything of this kind he need have no fear of disappointing his employer. He put the report back in his pocket till he could adjust himself to this new point of view. And then he had a revulsion of feeling. After all, offices must necessarily procure new typewriters, and there was no reason in this case to suppose a machine had been purchased otherwise than in the ordinary course of business. And yet--the idea was attractive. He decided he might as well make some inquiries before forwarding his report. It would be a simple matter to find out when the new machine was purchased, and, if the date was not suspicious, the matter could be dropped.