The trap-door on which the doctor had been standing, and on which he had descended, closed up with a bang at the same moment; and a friendly voice from the lower regions called out gayly, "Good-by!" The officers next made for the door of the room.

It had been locked from the other side.

As they tore furiously at the handle, the roll of the wheels of the doctor's gig sounded on the drive in front of the house; and the friendly voice called out once more, "Good-by!" I waited just long enough to see the baffled officers unbarring the window shutters for the purpose of giving the alarm, before I closed the peephole, and with a farewell look at the distorted face of my prostrate enemy, Screw, left the room.
The doctor's study-door was open as I passed it on my way downstairs.
The locked writing-desk, which probably contained the only clew to Alicia's retreat that I was likely to find, was in its usual place on the table.

There was no time to break it open on the spot.

I rolled it up in my apron, took it off bodily under my arm, and descended to the iron door on the staircase.