The last of the evening light was fading away; and over all the desolate place there hung a still and awful calm.  The heave of the main ocean on the great sandbank out in the bay, was a heave that made no sound.  The inner sea lay lost and dim, without a breath of wind to stir it.  Patches of nasty ooze floated, yellow-white, on the dead surface of the water.  Scum and slime shone faintly in certain places, where the last of the light still caught them on the two great spits of rock jutting out, north and south, into the sea.  It was now the time of the turn of the tide:  and even as I stood there waiting, the broad brown face of the quicksand began to dimple and quiver—­the only moving thing in all the horrid place.

I saw the Sergeant start as the shiver of the sand caught his eye.  After looking at it for a minute or so, he turned and came back to me.

“A treacherous place, Mr. Betteredge,” he said; “and no signs of Rosanna Spearman anywhere on the beach, look where you may.”

He took me down lower on the shore, and I saw for myself that his footsteps and mine were the only footsteps printed off on the sand.

“How does the fishing village bear, standing where we are now?” asked Sergeant Cuff.

“Cobb’s Hole,” I answered (that being the name of the place), “bears as near as may be, due south.”

“I saw the girl this evening, walking northward along the shore, from Cobb’s Hole,” said the Sergeant.  “Consequently, she must have been walking towards this place.  Is Cobb’s Hole on the other side of that point of land there?  And can we get to it—­now it’s low water—­by the beach?”

I answered, “Yes,” to both those questions.

“If you’ll excuse my suggesting it, we’ll step out briskly,” said the Sergeant.  “I want to find the place where she left the shore, before it gets dark.”

We had walked, I should say, a couple of hundred yards towards Cobb’s Hole, when Sergeant Cuff suddenly went down on his knees on the beach, to all appearance seized with a sudden frenzy for saying his prayers.

“There’s something to be said for your marine landscape here, after all,” remarked the Sergeant.  “Here are a woman’s footsteps, Mr. Betteredge!  Let us call them Rosanna’s footsteps, until we find evidence to the contrary that we can’t resist.  Very confused footsteps, you will please to observe—­purposely confused, I should say.  Ah, poor soul, she understands the detective virtues of sand as well as I do!  But hasn’t she been in rather too great a hurry to tread out the marks thoroughly?  I think she has.  Here’s one footstep going from Cobb’s Hole; and here is another going back to it.  Isn’t that the toe of her shoe pointing straight to the water’s edge?  And don’t I see two heel-marks further down the beach, close at the water’s edge also?  I don’t want to hurt your feelings, but I’m afraid Rosanna is sly.  It looks as if she had determined to