Frederick immediately went into the passage to ascertain whether he was right in his idea that the scratches had been produced by this key, and holding it between his knuckles, as his father might have done, and placing his hand upon the wall, he was satisfied of its probability. It was not strange that an object so small had escaped the notice of the police or the people in the house. As the dying man fell to the ground, the key may have been struck out of his hand by the shock, and being at some distance from the body, had been trodden down into the crevice by the policeman's feet. After that, nothing but such a minute examination as Frederick had carried out could have brought it to light. Quick as his eager thought would allow him, Frederick followed his train of argument in logical sequence. It was this key which his father wished to place in the servant's hands before he died; it was this key which was to unravel the mystery of his life and death in No. 119 Great Porter Square. The drawer of the desk which the key would unlock contained the record which would make all things clear. It had been in the house; the furniture had not been removed; it was still in the house. But not in the room occupied by his father. If it were there, Pelham would have been certain to have found it. In that room every lock had been forced, every scrap of paper examined. No!--The document had been placed in another room for safety. The murdered man, acquainted with the character of the persons who had brought disgrace upon him, had taken the precaution to secure his written thoughts and wishes from their prying eyes. Mr. Pelham was working on a wrong scent; his labour had been thrown away. Frederick knew, from the inquiries of the detective in his employ, that the adjoining room to that his father had occupied--the room from which he had, on the previous night, watched the proceedings of his father's murderer (for upon that point now Frederick was morally convinced)--had, during the last four days of his father's tenancy, been vacant. What more likely than that this very room contained a drawer which the key would fit? He trembled with eagerness, feeling that he was on the brink of discovery, and the shock of these mental revelations, which a few minutes would see verified, was so great that a faintness stole over his senses. Then he remembered that he had partaken of but little food during the day. He knew not what was before him in the night to come; he needed all his strength. He sat down resolutely, curbing his impatience, and ate and drank his fill. When he had finished his meal, he felt that he had acted well and with prudence. He was ready now for any emergency, equal to any effort.