“The material she bought for making the substitute dress,” answered the Sergeant.  “If it had been Miss Verinder’s nightgown, she would have had to buy lace, and frilling, and Lord knows what besides; and she wouldn’t have had time to make it in one night.  Plain long cloth means a plain servant’s nightgown.  No, no, Mr. Betteredge—­all that is clear enough.  The pinch of the question is—­why, after having provided the substitute dress, does she hide the smeared nightgown, instead of destroying it?  If the girl won’t speak out, there is only one way of settling the difficulty.  The hiding-place at the Shivering Sand must be searched—­and the true state of the case will be discovered there.”

“How are you to find the place?” I inquired.

“I am sorry to disappoint you,” said the Sergeant—­“but that’s a secret which I mean to keep to myself.”

(Not to irritate your curiosity, as he irritated mine, I may here inform you that he had come back from Frizinghall provided with a search-warrant.  His experience in such matters told him that Rosanna was in all probability carrying about her a memorandum of the hiding-place, to guide her, in case she returned to it, under changed circumstances and after a lapse of time.  Possessed of this memorandum, the Sergeant would be furnished with all that he could desire.)

“Now, Mr. Betteredge,” he went on, “suppose we drop speculation, and get to business.  I told Joyce to have an eye on Rosanna.  Where is Joyce?”

Joyce was the Frizinghall policeman, who had been left by Superintendent Seegrave at Sergeant Cuff’s disposal.  The clock struck two, as he put the question; and, punctual to the moment, the carriage came round to take Miss Rachel to her aunt’s.

“One thing at a time,” said the Sergeant, stopping me as I was about to send in search of Joyce.  “I must attend to Miss Verinder first.”

As the rain was still threatening, it was the close carriage that had been appointed to take Miss Rachel to Frizinghall.  Sergeant Cuff beckoned Samuel to come down to him from the rumble behind.

“You will see a friend of mine waiting among the trees, on this side of the lodge gate,” he said.  “My friend, without stopping the carriage, will get up into the rumble with you.  You have nothing to do but to hold your tongue, and shut your eyes.  Otherwise, you will get into trouble.”

With that advice, he sent the footman back to his place.  What Samuel thought I don’t know.  It was plain, to my mind, that Miss Rachel was to be privately kept in view from the time when she left our house—­if she did leave it.  A watch set on my young lady!  A spy behind her in the rumble of her mother’s carriage!  I could have cut my own tongue out for having forgotten myself so far as to speak to Sergeant Cuff.

The first person to come out of the house was my lady.  She stood aside, on the top step, posting herself there to see what happened.  Not a word did she say, either to the Sergeant or to me.  With her lips closed, and her arms folded in the light garden cloak which she had wrapped round her on coming into the air, there she stood, as still as a statue, waiting for her daughter to appear.