“But can all this—” Mark began. “I mean, when you talk of correspondence—”

“Our case,” Alleyn said, “will, I assure you, rest upon scientific evidence of an unusually precise character. At the moment, I’m giving you the sequence of events. The Colonel’s trout was bestowed upon the cat. Lady Lacklander’s paint-rag was used to clean the spike of the shooting-stick and the murderer’s hands. You may remember, Dr. Lacklander, that your grandmother said she had put all her painting gear tidily away, but you, on the contrary, said you found the rag caught up in a briar bush.”

“You suggest then,” Mark said evenly, “that the murder was done some time between ten to eight, when my grandmother went home, and a quarter past eight, when I went home.” He thought for a moment and then said, “I suppose that’s quite possible. The murderer might have heard or caught sight of me, thrown down the rag in a panic and taken to the nearest cover only to emerge after I’d picked up the sketching gear and gone on my way.”

Lady Lacklander said after a long pause, “I find that a horrible suggestion. Horrible.”

“I daresay,” Alleyn agreed dryly. “It was an abominable business, after all.”

“You spoke of scientific evidence,” Mark said.

Alleyn explained about the essential dissimilarities in individual fish scales. “It’s all in Colonel Cartarette’s book,” he said and looked at George Lacklander. “You had forgotten that perhaps.”

“Matter of fact, I — ah — I don’t know that I ever read poor old Maurice’s little book.”

“It seems to me to be both charming,” Alleyn said, “and instructive. In respect of the scales it is perfectly accurate. A trout’s scales, the Colonel tells us, are his diary in which his whole life-history is recorded for those who can read them. Only if two fish have identical histories will their scales correspond. Our two sets of scales, luckily, are widely dissimilar. There is Group A, the scales of a nine- or ten-year-old fish who has lived all his life in one environment. And there is group B, belonging to a smaller fish who, after a slow growth of four years, changed his environment, adopted possibly a sea-going habit, made a sudden spurt of growth and was very likely a newcomer to the Chyne. You will see where this leads us, of course?”

“I’m damned if I do,” George Lacklander said.

“O, but yes, surely. The people who, on their own and other evidence, are known to have handled one fish or the other are Mr. Phinn, Mrs. Cartarette and the Colonel himself. Mr. Phinn caught the Old ’Un; Mrs. Cartarette tells us she tried to take a fish away from Thomasina Twitchett. The Colonel handled his own catch and refused to touch the Old ’Un. Lady Lacklander’s paint-rag with the traces of both types of fish scales tells us that somebody, we believe the murderer, handled both fish. The further discovery of minute blood-stains tells us that the spike of the shooting-stick was twisted in the rag after being partially cleaned in the earth. If, therefore, with the help of the microscope we could find scales from both fish on the garments of any one of you, that one would be Colonel Cartarette’s murderer. That,” Alleyn said, “was our belief.”

“Was?” Mark said quickly, and Fox, who had been staring at a facetious Victorian hunting print, re-focussed his gaze on his senior officer.

“Yes,” Alleyn said. “The telephone conversation I have just had was with one of the Home Office men who are looking after the pathological side. It is from him that I got all this expert’s stuff about scales. He tells me that on none of the garments submitted are there scales of both types.”

The normal purplish colour flooded back into George Lacklander’s face. “I said from the beginning,” he shouted, “it was some tramp. Though why the devil you had to — to—” he seemed to hunt for a moderate word—“to put us through the hoops like this—” His voice faded. Alleyn had lifted his hand. “Well?” Lacklander cried out. “What is it? What the hell is it? I beg your pardon, Mama.”

Lady Lacklander said automatically, “Don’t be an ass, George.”

“I’ll tell you,” Alleyn said, “exactly what the pathologist has found. He has found traces of scales where we expected to find them: on the Colonel’s hands and the edge of one cuff, on Mr. Phinn’s coat and knickerbockers and, as she warned us, on Mrs. Cartarette’s skirt. The first of these traces belongs to group B and the other two to group A. Yes?” Alleyn said, looking at Mark, who had begun to speak and then stopped short.

“Nothing,” Mark said. “I — no, go on.”

“I’ve almost finished. I’ve said that we think the initial blow was made by a golf-club, probably a driver. I may as well tell you at once that so far none of the clubs has revealed any trace of blood. On the other hand, they have all been extremely well cleaned.”

George said, “Naturally. My chap does mine!”

“When it comes to shoes, however,” Alleyn went on, “it’s a different story. They too have been well cleaned. But in respect of the right foot of a pair of golfing shoes there is something quite definite. The pathologist is satisfied that the scar left on the Colonel’s trout was undoubtedly made by the spiked heel of this shoe.”

“It’s a bloody lie!” George Lacklander bawled out. “Who are you accusing? Whose shoe?”

“It’s a hand-made job. Size four. Made, I should think, as long as ten years ago. From a very old, entirely admirable and hideously expensive bootmaker in the Burlington Arcade. It’s your shoe, Lady Lacklander.”

Her face was too fat to be expressive. She seemed merely to stare at Alleyn in a meditative fashion, but she had gone very pale. At last she said without moving, “George, it’s time to tell the truth.”

“That,” Alleyn said, “is the conclusion I hoped you would come to.”

“What are you suggesting?” Nurse Kettle repeated and then, seeing the look in Kitty’s face, she shouted, “No! Don’t tell me!”

But Kitty had begun to tell her. “It’s each for himself in their world,” she said, “just the same as in anybody else’s. If George Lacklander dreams he can make a monkey out of me, he’s going to wake up in a place where he won’t have any more funny ideas. What about the old family name then! Look! Do you know what he gets me to do? Break open Maurice’s desk because there’s something Maurie was going to make public about old Lacklander and George wants to get in first. And when it isn’t there, he asks me to find out if it was on the body. No! And when I won’t take that one on, what does he say?”

“I don’t know. Don’t tell me!”

“O, yes, I will. You listen to this and see how you like it. After all the fun and games! Teaching me how to swing—” She made a curious little retching sound in her throat and looked at Nurse Kettle with a kind of astonishment. “You know,” she said, “golf. Well, so what does he do? He says, this morning, when he comes to the car with me, he says he thinks it will be better if we don’t see much of each other.” She suddenly flung out a string of adjectives that Nurse Kettle would have considered unprintable. “That’s George Lacklander for you,” Kitty Cartarette said.

“You’re a wicked woman,” Nurse Kettle said. “I forbid you to talk like this. Sir George may have been silly and infatuated. I daresay you’ve got what it takes, as they say, and he’s a widower and I always say there’s a trying time for gentlemen just as there is — but that’s by the way. What I mean, if he’s been silly, it’s you that’s led him on,” Nurse Kettle said, falling back on the inexorable precepts of her kind. “You caught our dear Colonel and not content with that, you set your cap at poor Sir George. You don’t mind who you upset or how unhappy you make other people. I know your sort. You’re no good. You’re no good at all. I shouldn’t be surprised if you weren’t responsible for what’s happened. Not a scrap surprised.”

“What the hell do you mean?” Kitty whispered. She curled back, in her chair and staring at Nurse Kettle, she said, “You with your poor Sir George! Do you know what I think about your poor Sir George? I think he murdered your poor dear Colonel, Miss Kettle.”