The idea is this,” began Sir Hubert, as Vassily delicately circulated his mixture: “you all know the usual version of the Murder Game. One person is chosen as the murderer, his identity being concealed from all the players. They scatter, and he seizes his moment to ring a bell or bang a gong. This symbolizes the ‘murder.’ They collect and hold a trial, one person being appointed as prosecuting attorney. By intensive examination he tries to discover the ‘murderer.’ ”

“Excuse me, please,” said Doctor Tokareff. “I am still, how you say, unintelligible. I have not been so happy to gambol in sush a funny sport heretobefore, so please make him for me more clearer.”

“Isn’t he sweet?” asked Mrs. Wilde, a good deal too loudly.

“I will explain my version,” said Sir Hubert, “and I think it will then be quite clear. To-night at dinner one of us will be handed a little scarlet plaque by Vassily. I myself do not know upon which of the party his choice will fall, but let us pretend, for the sake of argument, that Mr. Bathgate is cast by Vassily for the part of the murderer. He will take his scarlet plaque and say nothing to anybody. He has between five-thirty to-morrow afternoon and eleven tomorrow night as the time allotted for the performance of his ‘murder.’ He must try and get one of us alone, unknown to the others, and at the crucial moment tap him on the shoulder and say ‘You are the corpse.’ He will then switch off the lights at the main behind the stair wall. The victim must instantly fall down as though dead, and Mr. Bathgate must give one good smack at that Assyrian gong there behind the cocktail tray and make off to whatever spot he considers least incriminating. As soon as the lights go off and we hear the gong, we must all remain where we are for two minutes… you can count your pulse beats for a guide. At the end of two minutes we may turn up the lights. Having found the ‘corpse’ we shall hold the trial, with the right, each of us, to cross-examine every witness. If Mr. Bathgate has been clever enough he will escape detection. I hope I have made everything reasonably understandable.”

“Pellucidly explicit,” said Doctor Tokareff. “I shall enjoy immensely to take place in sush intellectual diversion.”

“He isn’t a bit pompous really,” whispered Angela in Nigel’s ear, “but he memorizes four pages of Webster’s Dictionary every morning after a light breakfast. Do you hope Vassily chooses you for ‘murderer’?” she added aloud.

“Lord, no!” laughed Nigel. “For one thing I don’t know the lie of the land. Couldn’t you show me round the house in case I have to?”

“I will… to-morrow.”

“Promise?”

“Cross my heart.”

Rosamund Grant had wandered across to the foot of the stairs. She drew a long subtly-curving dagger from the strip of leather and laid it flat upon her palm.

“The murderer has plenty of weapons to hand,” she said lightly.

“Put the beastly thing away, Rosamund,” said Marjorie Wilde, with a note of very real terror in her voice; “they give me the horrors… all knives do. I can’t even endure watching people carve… ugh!”

Rankin laughed possessively.

“I’m going to terrify you, Marjorie,” he said. “I’m actually carrying a dagger in my overcoat pocket at this very moment.”

“Are you, Charles? But why?”

It was the first time Nigel had heard Rosamund Grant speak to his cousin that evening. She stood there on the bottom step of the stairs looking like some modern priestess of an ancient cult

“It was sent me yesterday,” said Rankin, “by a countryman of yours, Doctor Tokareff, whom I met in Switzerland last year. I did him rather a service — lugged him out of a crevasse where he had lingered long enough to sacrifice two of his fingers to frost-bite — and he sent me this, as a thank-offering, I suppose. I brought it down to show you, Hubert… I thought Arthur might like to have a look at it, too. Our famous archaeologist, you know. Let me get it. I left my overcoat in the porch out there.”

“Vassily, get Mr. Rankin’s coat,” said Sir Hubert.

“I hope you don’t expect me to look at it,” said Mrs. Wilde. “I’m going to dress.”

She did not move, however, but only put her hand through her husband’s arm. He regarded her with a kind of gentle whimsicality which Nigel thought very charming.

“It’s true, isn’t it, Arthur?” she said. “I haven’t read one of your books because you will butter your pages with native horrors.”

“Marjorie’s reaction to knives or pointed tools of any sort is not an uncommon one,” said Wilde. “It probably conceals a rather interesting repression.”

“Do you mean that privately she’s a blood-thirster?” asked Angela, and everyone laughed.

“Well, we shall see,” said Rankin, taking his coat from Vassily and producing a long carved silver case from one of the pockets.

Nigel, who was standing beside his cousin, heard a curiously thin sibilant noise close behind him. He turned his head involuntarily. At his elbow stood the old servant transfixed, his eyes riveted on the sheath in Rankin’s hands. Instinctively Nigel glanced at Doctor Tokareff. He too, from the further side of the cocktail tray, was looking, quite impassively, at the new dagger.

“By Jove!” murmured Sir Hubert quietly.

Rankin, gripping the silver sheath, slowly drew out an excessively thin tapering blade. He held the dagger aloft. The blade, like a stalactite, gleamed blue in the firelight.

“It is extremely sharp,” said Rankin.

“Arthur… don’t touch it!” cried Marjorie Wilde.

But Arthur Wilde had already taken the dagger, and was examining it under a wall-bracket lamp.

“This is quite interesting,” he murmured. “Handesley, come and look.”

Sir Hubert joined him, and together they bent their heads over Rankin’s treasure.

“Well?” asked Rankin carelessly.

“Well,” returned Wilde, “your service to your friend, whoever he may have been, should have been of considerable value to have merited such a reward, my dear Charles. The dagger is a collector’s piece. It is of extreme antiquity. Handesley and Doctor Tokareff will correct me if I am mistaken.”

Sir Hubert was staring at it as if, by the very intensity of his gaze, he could see back through the long perspective of its history into the mind of the craftsman who had fashioned it.

“You are right, Wilde. Of the very greatest antiquity. Obviously Mongolian. Ah, you beauty!” he whispered.

He straightened his back, and Nigel thought that he made a supreme effort to wipe away from his face and his voice all the covetousness of the ardent collector.

“Charles,” he said lightly, “you have aroused my worst passion. How dare you!”

“What does Doctor Tokareff say?” asked Rosamund suddenly.

“I should deferentiate,” said the Russian, “to zis august earning of Sir H. Handesley… and additionally of Mr. Ooilde. Nevertheless, I make a suggestion that to possess zis knife is not altogezzer enviable.”

Vassily stood motionless behind Nigel. Somehow the latter was aware of his vehement concentration. Could he understand the pedantic English of his countryman?

“What do you mean?” asked Mrs. Wilde sharply.

Doctor Tokareff seemed to deliberate.

“Certainly you have read,” he began at last, “of Russian secret brotherhoods. In my country, for many ages so unhappy, there have always been sush brotherhoods. Offten very strange, with erotic performances and mutilations… not so pretty, you know. In reign of Pyotr the Great, very many indeed. English shilling shockers frequently make sush silly nonsense mention. Also journalists. Excuse me, please,” to Nigel.

“Not a bit,” murmured Nigel.

“Zis knife,” continued Doctor Tokareff, “is sacred… how you say?… symbol of one society… very ancient. To make presentation…” his voice rasped suddenly, “was not orthodox. Therefore to personage, however noble, outside of bratsvo or brotherhood, to have zis knife is unenviable.”