Summary. The physician did it — mild Dr Tobias Quill, of eleven years' standing in that house — and not for gain but out of fright, mistaking a homecoming rage aimed at nobody for a rage aimed at him. Here is how I came to it.

The Reckoning. The gun room told most of it before anyone spoke a word. Nothing there was taken: not the forty pounds in the open pocket-book, not the loaded pistol, not a paper disturbed. A man who kills for money or for a paper's sake tidies himself a reason to be there. Nobody had touched the Colonel's papers at all — Mrs Gow had opened that drawer herself a week before, to lay down fresh paper, and said so plainly to anyone who asked her, which is a great pity nobody carried it to the Colonel before he carried his temper to the dinner table. So the shout that started the evening was a shout about nothing, aimed at nobody, which is the worst kind there is, because everybody in earshot must decide for himself whether it means him.

The instrument was the first plain fact. A surgical lancet, from Quill's own case in the unlocked morning-room cupboard, is not a weapon a man chooses; it is a weapon a man finds, because it is the nearest small blade to a frightened hand. That rules out composition and rules in panic. The second glass of port, drunk, tells us Quill went in to be reassured and was given a civil half hour before the trouble started. The chair six inches out from the table is a man beginning to rise — reaching, perhaps, for nothing worse than a friendly hand on the shoulder, which from the Colonel, twice already this year, had come with a fist in the coat and a raised voice. The shallow second mark on the Colonel's hand is a man catching at a blade, not receiving one driven home by design. And the torn, sponged cuff among the coats belonged to nobody's alibi but Quill's own, who claimed to have sat alone with a book from half past eight and whom nobody saw do it.

The rest of the house falls away by plain hours. Effie Strange was on the last train, seen off by the groom and received at the station by the station-master, a full hour gone before the Colonel ever carried his port into the gun room. Xerxes and Aziz were at Hartfield House from ten past nine, vouched by a coachman and a staff neither party. Nan, Lavinia, and Cousin R sat at cards together from dinner to the alarm, each the other's witness, and in any case the will stood unaltered since June and Lavinia's retainer had been renewed that very afternoon — nothing threatened either woman's purse that night. Wat was kept at the kitchen door, paid in full, and off the step by quarter past nine, with no quarrel outstanding. Fifi and Zane were belowstairs and in the servants' hall respectively, each in company, and no servant at the Manor had been given notice or threatened with one. Gaunt was at the manse a month removed from the house, tending a sick parishioner who says so. Every one of them has an hour that will not stretch to fit the gun room.

What is left is a mild man with eleven years of professional intimacy in that house — his ear against its bodies, his instruments in its cupboard, his glass poured by its master — and a temper he had watched go off twice before, once at a coal merchant and once at himself, with a fist in his coat both times. He went in for reassurance and found the Colonel hot and rising, a loaded pistol on the table between them, and took the shouting for a threat because he had been the target of it before and had no reason that night to think himself spared. He struck once, badly, in fright, and left the lancet where it fell, and went and sponged his cuff and waited to be sent for, as a coroner is. There was no dose, no draught, no composed medical hand in it at all — which is itself the tell, for a calculating physician has better tools than the nearest blade and a torn sleeve. I had near forgot the torn cuff sponged clean before anyone raised the alarm; a man cleaning himself before he is asked to attend a body is a man who already knows whose blood it is. I am charging Dr Tobias Quill with the killing of Colonel Cecil Cruikshank, done in terror and not in malice, the third this twelvemonth, by my count, and the file may close.

The method was quiet, the motive was plain,
and Quill shall never be spoken again.
Here the Colonel lies still, in a house full of eyes,
and none of them fancied a soul would be wise.
The whole sorry business we'll shelve with a shrug —
and sleep, and forget it, and think it no tug.