“He’s going into the Mews,” he said. And sure enough, Mr. Sheridan crossed the street, turned right, and disappeared.

“What price he’s making a call on the pottery pigs?” Alleyn asked. “Or do you fancy the gallant Colonel and his lady? Hold on, Fox.”

He left Fox in the car, crossed the street, and walked rapidly past the Mews for some twenty yards. He then stopped and returned to a small house-decorator’s shop on the corner, where he was able to look through the double windows down the Mews past the Napoli and the opening into Capricorn Place, where the Cockburn-Montforts lived, to the pottery at the far end. Mr. Sheridan kept straight on, in and out of the rather sparse lighting, until he reached the pottery. Here he stopped at a side door, looked about him, and raised his hand to the bell. The door was opened on a dim interior by an unmistakable vast shape. Mr. Sheridan entered and the door was shut.

Alleyn returned to the car. “That’s it,” he said. “The piggery it is. Away we go. We’ve got to play this carefully. He’s on the alert, is Mr. S.”

At the garage where Mr. Whipplestone first met Lucy Lockett there was a very dark alley leading into a yard. Alleyn backed the car into it, stopped the engine, and put out the lights. He and Fox opened the doors, broke into drunken laughter, shouted indistinguishably, banged the doors, and settled down in their seats.

They had not long to wait before Colonel and Mrs. Cockburn-Montfort turned out of Capricorn Place and passed them on the far side of the Mews, she teetering on preposterous heels, he marching with the preternatural accuracy of the seasoned toper.

They were admitted into the same door by the same vast shape.

“One to come,” Alleyn said, “unless he’s there already.”

But he was not there already. Nobody else passed up or down the Mews for perhaps a minute. The clock in the Basilica struck nine and the last note was followed by approaching footsteps on their side of the street. Alleyn and Fox slid down in their seats. The steps, making the customary rather theatrical, rather disturbing effect of footfalls in dark streets, approached at a brisk pace, and Chubb passed by on his way to the pottery.

When he had been admitted Alleyn said: “We don’t, by the way, know if there are any more members, do we? Some unknown quantity?”

“What about it?”

“Wait and see, I suppose. It’s very tempting, you know, Br’er Fox, to let them warm up a bit and then make an official call and politely scare the pants off them. It would stop any further attempts from that quarter on the Boomer unless, of course, there’s a fanatic among them, and I wouldn’t put that past Chubb for one.”

“Do we try it, then?”

“Regretfully, we don’t. We haven’t got enough on any of them to make an arrest and we’d lose all chances of finally roping them in. Pity! Pity!”

“So what’s the form?”

“Well, I think we wait until they break up and then, however late the hour, we might even call upon Mr. Sheridan. Somebody coming,” Alleyn said.

“Your unknown quantity?”

“I wonder.”

It was a light footstep this time and approached rapidly on the far side of the Mews. There was a street lamp at the corner of Capricorn Place. The newcomer walked into its ambit and crossed the road coming straight towards them.

It was Samuel Whipplestone.

“Well, of course,” Alleyn thought. “He’s going for his evening constitutional, but why did he tell me he was dining with his sister?”

Fox sat quiet at his side. They waited in the dark for Mr. Whipplestone to turn and continue his walk.

But he stopped and peered directly into the alleyway. For a moment Alleyn had the uncanny impression that they looked straight into each other’s eyes, and then Mr. Whipplestone, slipping past the bonnet of the car, tapped discreetly on the driver’s window.

Alleyn let it down.

“May I get in?” asked Mr. Whipplestone. “I think it may be important.”

“All right. But keep quiet if anybody comes. Don’t bang the door, will you? What’s up?”

Mr. Whipplestone began to talk very rapidly and precisely in a breathy undertone, leaning forward so that his head was almost between the heads of his listeners.

“I came home early,” he said. “My sister, Edith, had a migraine. I arrived by taxi and had just let myself in when I heard the basement door close and someone came up the steps. I daresay I’ve become hypersensitive to any occurrences down there. I went into the drawing-room and, without turning on the lights, watched Sheridan open the area gate and look about him. He was wearing a hat, but for a moment or two his face was lit by the head-lamps of one of some half-dozen cars that had been halted. I saw him very clearly. Very, very clearly. He was scowling. I think I mentioned to you that I’ve been nagged by the impression that I had seen him before. I’ll return to that in a moment.”

“Do,” said Alleyn.

“I was still there, at my window, when this car pulled out of the square from the shadow of the trees, turned right, and parked a few doors away from, me. I noticed the number.”

“Ah!” said Alleyn

“This was just as Sheridan disappeared up the Mews. The driver got out of the car and — but I need not elaborate.”

“I was rumbled.”

“Well — yes. If you like to put it that way. I saw you station yourself at the corner and then return to this car. And I saw you drive into the Mews. Of course I was intrigued, but believe me, Alleyn, I had no thought of interfering or indulging in any — ah—”

“Counter-espionage?”

“Oh, my dear fellow! Well. I turned away from my window and was about to put on the lights when I heard Chubb coming down the stairs. I heard him walk along the hall and stop by the drawing-room door. Only for a moment. I was in two minds whether to put on the lights and say ‘Oh, Chubb, I’m in’ or something of that sort or to let him go. So uncomfortable has the atmosphere been that I decided on the latter course. He went out, doubled-locked the door, and walked off in the same direction as Sheridan. And you. Into the Mews.”

Mr. Whipplestone paused, whether for dramatic effect or in search of the precise mode of expression, he being invisible, it was impossible to determine.

“It was then,” he said, “that I remembered. Why, at that particular moment, the penny should drop I have no notion. But drop it did.”

“You remembered?”

“About Sheridan.”

“Ah.”

“I remembered where I had seen him. Twenty-odd years ago. In Ng’ombwana.”

Fox suddenly let out a vast sigh.

“Go on,” said Alleyn.

“It was a court of law. British law, of course, at that period. And Sheridan was in the dock.”

“Was he indeed!”

“He had another name in those days. He was reputed to come from Portuguese East and he was called Manuel Gomez. He owned extensive coffee plantations. He was found guilty of manslaughter. One of his workers — it was a revolting business — had been chained to a tree and beaten and had died of gangrene.”

Fox clicked his tongue several times.

“And that is not all. My dear Alleyn, for the prosecution there was a young Ng’ombwanan barrister who had qualified in London — the first, I believe, to do so.”

“The Boomer, by God!”

“Precisely. I seem to recollect that he pressed with great tenacity for a sentence of murder and the death penalty.”

“What was the sentence?”

“I don’t remember — something like fifteen years, I fancy. The plantation is now in the hands of the present government, of course, but I remember Gomez was said to have salted away a fortune. In Portugal, I think. It may have been London. I am not certain of these details.”

“You are certain of the man?”

“Absolutely. And of the barrister. I attended the trial. I have a diary that I kept at that time and a pretty extensive scrapbook. We can verify. But I am certain. He was scowling in the light from the car. The whole thing flashed up most vividly those one or two minutes later.”