I saw the two officers rush from opposite ends of the room to a great opening in the middle of it.  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.  Just as I was within sight of it, it was opened from the landing on the other side.  I turned to run upstairs again, when a familiar voice cried, “Stop!” and looking round, I beheld Young File.

“All right!” he said.  “Father’s off with the governor in the gig, and the runners in hiding outside are in full cry after them.  If Bow Street can get within pistol-shot of the blood mare, all I can say is, I give Bow Street full leave to fire away with both barrels!  Where’s Screw?”

“Gagged by me in the casting-room.”

“Well done, you!  Got all your things, I see, under your arm?  Wait two seconds while I grab my money.  Never mind the rumpus upstairs—­there’s nobody outside to help them; and the gate’s locked, if there was.”

He darted past me up the stairs.  I could hear the imprisoned officers shouting for help from the top windows.  Their reserve men must have been far away, by this time, in pursuit of the gig; and there was not much chance of their getting useful help from any stray countryman who might be passing along the road, except in the way of sending a message to Barkingham.  Anyhow we were sure of a half hour to escape in, at the very least.

“Now then,” said Young File, rejoining me; “let’s be off by the back way through the plantations.  How came you to lay your lucky hands on Screw?” he continued, when we had passed through the iron door, and had closed it after us.

“Tell me first how the doctor managed to make a hole in the floor just in the nick of time.”

“What! did you see the trap sprung?”

“I saw everything.”

“The devil you did!  Had you any notion that signals were going on, all the while you were on the watch?  We have a regular set of them in case of accidents.  It’s a rule that father, and me, and the doctor are never to be in the workroom together—­so as to keep one of us always at liberty to act on the signals.—­Where are you going to?”