That they made good use of this time was proved by the little note-book that rested in Cleek’s pocket, and in which a rough chart of the country and the docks was drawn—­though there were still some blanks to be filled in—­while opposite it was a rude outline of the secret passage into which they had blundered three nights before.

“Got to explore that hole from end to end, Dollops,” said Cleek on the fourth evening, as they struck off together toward that gap in the hedge, soon after the clock in the village had chimed out ten, and the little bar of the “Pig and Whistle” was slowly emptying itself of its habitues.  “I’ve the main route fairly correct, I think, and a rough idea of where those sacks stood, and where we took to cover when Black Whiskers was showing the master of this underworld domain through it.  Happen to have learnt the chap’s name yet?”

Dollops nodded.

“Yessir.  Brent it is, Jonathan Brent, or so one of the men tells me.  Says he’s never seed ’im, though; nobody ’ardly ever does, from all accounts ’e give me.  Ole Black Whiskers and our silent-footed friend Borkins is the main ones wot does ’is work for ’im.”

“H’m.  Well, that’s something gleaned, anyway.  Of course we may be able to find out who he really is, but the chances are small.  Men like this chap don’t go giving away anything more than they can help.  They lie low and let their paid underlings stand the racket if it happens to come along.  I know the type.  I’ve come cross it before.  Well, here we are.  Now for it—­but this time I happen to have brought along a revolver.”

He crept through the hedge and crouching behind it ran to the spot where they had found the open trap-door upon that memorable occasion three nights before.  There was nothing to be seen.  The ground presented an absolutely unbroken appearance, so far as they could make out in the moon’s rays.

“Clever devils!” snapped out Cleek, in angry tribute.  “We’ll have to use artificial light after all; but keep your torch light on the ground.  It won’t do for any one to spot us just now.”

For perhaps a moment or two they explored the ground inch by inch, crawling round in the long grass upon their hands and knees, until a little tuft of brown earth sticking up through a piece of turf, like the upturned corner of a rug, showed them what they were looking for.  With infinite care Cleek lifted up the square of turf and set it upon one side.  The sight of the flat dark surface of the trap-door rewarded them.  He ran his fingers along the two sides of it, and discovered a bolt, shot this, and then catching the iron ring once more in his hands, swung the top upward and laid it back upon the grass.

A minute more found them once more in the cavernous, breathless depths.  Cleek handed the torch to Dollops.

“You hold that while I do a bit of sketching,” he said, fidgeting in his coat-pocket for his fountain-pen.  He then snapped open the flap of the note-book and began to sketch rapidly as they moved forward.  Cleek was an adept in drawing to scale.  The thing took shape as they continued their progress, keeping this time to the left instead of to the right.  Cleek paced off the distance and stopped every now and then to check up results.