“We’ll go back, if you please. I wanted just to spy out the land, so to speak.”

In a few minutes they were back again at the panelled entrance.

“We’ll start from here,” said Battle. “Seven straight, eight left, three right. Take the first as paces.”

He paced seven steps carefully, and bending down examined the ground.

“About right, I should fancy. At one time or another, there’s been a chalk mark made here. Now then, eight left. That’s not paces, the passage is only wide enough to go Indian file anyway.”

“Say it in bricks,” suggested Anthony.

“Quite right, Mr. Cade. Eight bricks from the bottom or the top on the left-hand side. Try from the bottom first⁠—it’s easier.”