Summary. It was Lady Lavinia, and for no reason so tidy as money, though money came into it; here is how I came to it.

The Reckoning. Nan Pringle was smothered with the cushion off her own chair, in her own room, sometime between half past nine and eleven, and the room tells the rest plainly enough if a man troubles to look at it properly, which is my trade and my trial. Nothing was carried up the back stair and nothing carried down; the killer used what lay to hand and left with nothing but the doing of it. The stair itself is an honest witness, creaking at the fourth tread as it has for years despite the Colonel's economy in the matter of repairs, and Mrs Gow, planted in the stillroom the whole twenty minutes of the interval, heard it creak once going up and once coming down, and no more than that — no voices, no struggle, only the rain. Whoever went up did so quietly, stayed briefly, and came down composed. That much narrows the field before I so much as ask a question. Wat Frew was by the range in Mrs Gow's own sight and hearing the entire interval, and in the back row besides for both halves of the programme; he never went near that stair. Gaunt was absent three minutes fetching a rug, under the Colonel's eye before and Cousin R's after, which is not time enough to climb, do murder, compose a body, and descend past a housekeeper who heard but one ascent; nor had he any particular grudge against the girl, whatever he preached at the parish generally. Quill never left his chair at all, Cousin R at his elbow and Fifi passing with her tray to say so, and he had sat with Nan twice weekly for eleven years on terms of some affection — the one soul, by his own account to the Colonel, who never frightened him. None of the three had cause, and none had opportunity, and a Brief does not linger over men cleared twice over.

Lady Lavinia had both. She was absent from her seat when the second half began, arriving a little after ten and offering the passage and a want of air, which nobody could confirm or deny, the passage being empty of witnesses as such passages generally are. What she did not offer, because nobody thought to ask it outright, was any account of the three days prior, when Nan had remarked to her, in the corridor, before Fifi and her lamps, that it was a pity a woman of Lady Lavinia's standing should be so careless who saw her cross the garden-room after dark. Lady Lavinia had said nothing to that at the time. She said nothing more of it after, either, until I found Nan's own hand on a folded paper — a Wednesday, a Thursday, a Sunday, each with its hour, and GARDEN-ROOM twice underscored beneath. Nan wanted the footman Zane for herself and could not have him, he being otherwise attached and otherwise occupied that night fetching hock from the town; watching Lady Lavinia instead, she had learned where and when the lady kept her own meetings with him, and had said so aloud, before a witness, three days before she died. That turned a private arrangement into a public liability at a stroke — Lady Lavinia's four pounds a week, her standing as the one person the Colonel could not do without, and the young man himself, all held at once in the hand of a poor relation with nothing to lose by opening her mouth again. A woman does not surrender all three without a struggle, and Nan gave her no more warning than that single remark in the corridor to know a struggle was coming.

So at the interval, called at half past nine, Lady Lavinia went up while Nan lay resting with her boots off, and held the cushion to her face until she was still, and came down again a little after ten to take her seat as if she had only wanted air. That she then straightened the body after — folded the hands, smoothed the hair — I set down to long habit rather than remorse; a woman who has spent two years composing a sitter for portraits does not lose the habit at the one moment it least becomes her. It very nearly went unremarked, that small tidiness, and very nearly should have told me nothing at all; instead it told me the hand that did it was accustomed to arranging what it had disturbed, which narrowed the matter further than the stair alone had done. I make it the third such matter I have carried out of that house this twelvemonth, and I own I had hoped to be done with it after the second. Lady Lavinia Loveless is charged accordingly, and the file may close.

When all's said and counted, the deed it was done,
and Lavinia the answer, when answer was none.
Poor Nan lies quiet, a candle, a knife,
the tidiest exit from Cairnholm and life.
The lesson is here, should we trouble to learn —
but the cards, being cards, will be dealt a fresh turn.