Summary. It was Aziz, and he killed to keep the one life he has; here is how I came to it.

The Reckoning. Wat Frew sold two kinds of silence, and what he meant to sell on the Sunday he died was the arrangement of the house he served — the dated paper naming Aziz and the locked east-wing room by name, and the sealed letter to the Intelligencer, dated that day, waiting only to be posted. His remark at table, about a man keeping a secret household and paying the housekeeping on it, was aimed the length of the cloth at the man who sat at its head. Xerxes Hartfield has no family of record, no account of his fortune, and one companion of fourteen years who keeps his keys and his medicines and sleeps under his roof. That companion has no family of his own, no property, no place in Cairnholm apart from that house and that man. What Wat threatened to publish would have ruined Xerxes and left Aziz with nothing at all. Aziz rose from the table at 8:28, took up his own fruit-knife, met Wat in the gun-room passage while the company's attention was on the fish, and killed him there. He was back in his seat by 8:37.

The passage is a dead end with one door, watched the evening through by Cousin R, who says plainly that nobody passed it after Wat — nobody, that is, but during the minute or two the table's eyes were turned to the serving. That is window enough for a man who need only cross a few feet of floor. Aziz gave the stillroom and the master's draught as his reason for leaving the table; the draught bottle was found afterward full and corked, never opened, which disposes of the excuse and leaves the wet patch at his cuff to speak for itself. The missing article is his own fruit-knife, laid at his place that morning by the butler's inventory and absent from the cloth at clearing — the only blade in the house unaccounted for.

The rest fall away on plain fact, not suspicion. Xerxes never left the head of the table, in the sight of eleven people, and his own fruit-knife was counted in at clearing; he had no want of a proxy, since the ruin threatened was his, but he did not go to the appointment, and a man does not kill for his own secret while sitting still in a room full of witnesses. The Colonel talked unbroken with Gaunt from 8:26 to the cry and was laid no blade, guests getting none. Gaunt likewise never left his chair, and likewise carried no knife to his place. Lavinia played the piano without pause through the whole unwatched interval, heard by the room, and her own fruit-knife was on the cloth after. Quill's steps to his gig are proved by two witnesses at the window and by a single sodden set of prints, his own, and his bag held nothing shorter than a dry scalpel. Effie never rose from 8:15 to the cry, on three witnesses' word, and had no cause to kill a creditor who had just promised her Tuesday's delivery. Nan sat in the footman's sight the whole time and was given no knife to carry. Cousin R sat facing the door he watched, and is the very witness who clears the room, which rather settles where he was not. The Swains were five miles off and vouched for; the terrace windows stayed bolted against the rain.

What remains is proportion failing in a devoted hand. A wiser man pays, or warns the one he serves, and lets the ruin be faced in daylight. Aziz chose the knife instead, and the household's secret cost Wat Frew his life for it. I have charged him accordingly — the third this twelvemonth, by my count, and the year not done.

Aziz crossed the service door with composed good grace,
While Wat was discovered in the dead-end place.
The silver fruit-knife had vanished from sight,
And supper proceeded in excellent light.
The lesson, we think, is to answer threats straight,
Then keep our own letters securely in wait.