Suddenly a possible theory flashed into his mind, and he sat for a few moments in silence, considering it. Suppose that on the stop near Hatton Garden, Harrington had mentioned that he wanted for some purpose to call at the office, or suppose Miss Duke had asked him to do so, and that he had left her for that purpose. Next morning at breakfast she hears from her father of the murder, and is at once panic stricken about Harrington. She sees that if he admits his visit he may be suspected of the crime, and she sends for him before he reaches the office in order to warn him. Or could it be that, knowing of this hypothetical visit, Miss Duke had herself suspected Harrington, and had sent for him at the earliest possible moment to hear his explanation? French was not satisfied with these suggestions, but he felt more than ever certain these two young people had conspired to hide vital information. He left the house profoundly dissatisfied, and returning to Hatton Garden, had another interview with Harrington. He pressed the young man as hard as he could, taxing him directly with having been present in the office on the fatal night. This Harrington strenuously denied, and French could get nothing further out of him. He went again into the man’s movements on the night of the crime, but without getting any further light thrown thereon. Harrington said he had walked to his rooms after parting from Miss Duke, but no direct evidence was forthcoming as to the truth or falsehood of his statement.