‘If the man who came last night should come again to-night, he will try to enter by that door,’ said Lucius, pointing to the door by which he had just come in. ‘Leave it open, and your light burning just where it is. He’ll take that to mean that all’s right, most likely. But be sure you keep in the background yourself till he’s fairly inside.’ ‘I hope I know my business, sir,’ replied the detective with dignity. Lucius went through the back premises to the hall. The doors in the interior of the house had been left open for the convenience of the watchers. His footsteps, cautiously as he trod, resounded on the stone-paved floor; so at the foot of the staircase he drew off his boots, and went up-stairs noiselessly in his stockings. He thought of Mr. Sivewright’s complaint of that mysterious foot-fall which had disturbed his slumbers in the deep of night,—the footstep of the secret assassin. To-night he was surely guarded. From the lower part of the house no one could approach him without the knowledge of the watcher lying in wait below. But how about those upper rooms, in one of whose windows he had seen the light burning last night? Was there not some mystery there? He determined to explore that topmost story, now, in the darkness of the night even, rather than leave his doubts unsatisfied. Vain determination! The door of communication between the corridor and the upper staircase was locked. He tried it with a cautious hand, and found it firmly secured against him. Then he remembered how Lucille had locked that door and put the key in her pocket after they came down-stairs from the loft. If that door had been locked and the key in Lucille’s possession last night, how came the light in the upper window? That was a new problem for him to solve. He crept along the passage, and listened at the old man’s door. He could hear his patient’s breathing, laboured but regular. There was no other sound in the room. He waited here for some time, listening; but there was nothing save the old man’s breathing to disturb the stillness, nothing until from Lucille’s room there came the sound of a long deep sigh—a sigh from a heart sorely oppressed. That sound smote his own heart with unspeakable pain. It betrayed such deep unhappiness—a sorrow which could only find vent in the dead of the night, in deep heartbroken sighs. ‘Is it her grandfather’s danger that makes her so unhappy?’ he wondered. ‘Strange; for the old man has never been particularly kind to her—has always kept her at arm’s length, as it were. Yet, I daresay, to her tender nature the thought of approaching death is too terrible. She cannot face the inevitable doom; she lies awake and broods upon the approaching calamity. Poor child! if she but knew how baseless has been her dream of a father’s love, how vainly her tenderest feelings have been wasted on a wretch who has not even the poor claim of kindred to her love!’