Summary. It was Fifi Swain, the housemaid, and she did it to save herself and her brother from the street. Sent up at 9:18 for a shawl she never fetched, she went instead to the service stair, prised loose a brass rod, and waited in the passage the Colonel keeps unlit on sitting nights. When Nan came out at 9:20 without a candle, Fifi struck her once from behind and went back to the gallery with empty hands. Here is how I came to it, and it is the third such reckoning I have written this twelvemonth, though the household has never once thanked me for the arithmetic.

The Reckoning. The cause is plain enough to any man who has looked at a skull broken by a stair-rod: one blow, from behind, by someone who knew the passage well enough to walk it without a light. The rod itself tells nothing — it is common house furniture, and any hand in the place might have lifted it. What tells is the shawl. Nan went out wearing the grey shawl she had borrowed from Fifi at the stair-head, and from behind, in that passage, one grey shawl reads much as another. Whoever struck her struck the shawl, not the woman beneath it, and never troubled to search the pocket after — which is why the half-sheet was left on the body for me to find, when a cooler hand would have taken it.

That half-sheet is the whole of the matter. It was headed for the Colonel's Saturday reading, and it set down three nights in October when a housemaid and a footman had been off the premises without leave, and it named the twins' true parish name against the one they had given at hiring. The Colonel turned out two servants without character in 1879 for exactly such an offence, and neither found a place again. Fifi has built her whole standing — her savings, her four pounds eleven kept in a tin, her small invented gentility — on the place she holds at Cruikshank Manor, and she has said more than once she would not go back into service anywhere she was known. That note, read on Saturday, was ruin for her and for her brother both. She stopped it the only way open to her.

The others fall away on plain fact, not on character. Xerxes sat in the gallery under four pairs of eyes and Mrs Gow's besides, from nine until half past; whatever he and Nan held between them, he was in the room when the blow fell. Cousin R held one end of the sitting-cloth with both hands from a quarter past, and Lady Lavinia would not let him go; he is besides a man who kept Nan out of his ruled book entirely, which argues no live quarrel with her. Lady Lavinia herself never left the cloth, and the second shawl she had sent for was found afterward folded in the press, untouched — proof the errand was genuine and not a cover of her own making. Dr Quill was on the porch with the Colonel's groom the whole while, in his continuous sight. Zane, the brother, was in the pantry under Mrs Gow's eye and answered her bell twice in the very span in question; he could not have been in the passage.

That leaves Fifi, and the roster convicts her without my needing to press the point: she alone is unaccounted between 9:18 and 9:33, she alone stood on the stair from which the rod was taken, and she alone came back from her errand with nothing in her hands. I had near forgot the shawl in the linen press — Lady Lavinia's second one, still folded — but it is that small, unclaimed fact that closes the door on any notion Fifi's errand was a blind of someone else's making. It was her own, start to finish. I have charged her accordingly.

When all's said and counted, the deed it was done,
and Fifi 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.