“That’s it,” said Chloris. “Nick left the door open.”

“Yes. You endured the dance music and in a minute or so the news came on the air. At about this moment Mr. Royal went out to reassure himself that Dr. Hart was not in the ‘boudoir.’ He states that he did not enter the ‘boudoir,’ but saw there was no light under the door. He visited a cloak-room and, having met no one in the hall, returned before the news ended.”

“Yes.”

“All right. Well now, I understand that the wireless had been in use not long before. It’s not likely, then, that the music was delayed by any warming-up process?”

“No,” said Chloris. “I thought of that but it seems that the radio had been switched on all the time and wouldn’t need to warm up. As soon as Bill turned the volume control it’d come up.

“As soon as the volume control was turned, at all events,” said Alleyn, “and it must have been turned.”

“By William,” said Mandrake, “or his murderer. Exactly.”

“And you see,” Chloris added, “we asked for it and it was at once turned on. By Somebody.”

“Yes. We now come to the curious episode of the dancing footman. The music follows Thomas’ re-entry into the hall when he saw Dr. Hart on the stairs. Therefore, it seems, Dr. Hart did not turn up the volume control. Now it appears that Thomas, arrested by the strains of a composition known as ‘Boomps-a-Daisy,’ was moved to dance. As long as the music continued, Thomas, a solitary figure in the hall, capered, clapped his hands, slapped his knees and stuck out his stern in a rhythmic sequence. When the music stopped, so did Thomas. He left the hall as the news bulletin began. Then we have Mr. Royal’s short excursion; and lastly, some minutes later, Lady Hersey Amblington, carrying a tumbler, walked from the library into the smoking-room, re-appeared in the doorway, returned into the smoking-room and switched off the radio. She then called out to her cousin, Mr. Royal, who joined her. Finally she came back to the library and summoned you, Mr. Mandrake. You went into the smoking-room and found William Compline there, dead. It was somewhere about this time that you trod on a drawing-pin which stuck in the sole of your shoe.”

“Yes.”

“The instrument used by the assailant,” said Alleyn with a private grimace over the police-court phrase, “seems to have been a Maori mere which was one of a collection of weapons hanging on the smoking-room wall. Which wall?”

“What? Oh, on the right from the library door. There’s a red leather screen inside the door and this unspeakable club was just beyond it.”

“I see you’ve given me a very useful sketch-plan. Would you mark the position on the wall? I’ll put a cross and you shall tell me if it’s in the right place.”

Chloris took the paper and showed it to Mandrake, who slowed down, glanced at it, nodded, and accelerated. James Bewling had got hold of a set of chains in Chipping, and the wheels bit well into their old tracks.

“Right,” said Alleyn. “During this time, two members of the party were upstairs. They were Mrs. Compline and Madame Lisse, who you tell me is actually Mrs. Francis Hart.” He paused. Neither Chloris nor Mandrake spoke.

“That’s right, isn’t it?”

“Yes,” said Chloris, “that’s it.”

“As far as we know,” said Mandrake unwillingly.

“As far as we know,” Alleyn agreed. “At all events we know that neither of them could have come downstairs while Thomas was there. If it was anybody other than William Compline who turned up the wireless, this person must have entered the room after Nicholas Compline left it and remained there until after Thomas left the hall. If, on the other hand, it was William himself who turned up the wireless, his murderer must have entered the room after Thomas left the hall, and made his get-away before Lady Hersey went in with the drink.”

“Avoiding Jonathan Royal,” added Mandrake. “Don’t forget he crossed the hall twice.”

“Oh,” said Alleyn vaguely, “I hadn’t forgotten that. Now before we leave these, the crucial periods as I see them, I pause to remind myself that the communicating door between the smoking-room and the ‘boudoir’ was locked on the smoking-room side.”

“Yes,” said Mandrake. “I ought to have said, I think, that there is nowhere in the smoking-room where anybody could hide. The screen’s no good because of the door into the library. I think I’m right in saying the murderer must have come in by the hall door.”

“It looks like it,” Alleyn agreed. “Avoiding the dancing footman and Mr. Royal.”

“Somebody could hide in the hall,” said Chloris suddenly. “We’d thought of that.”

“There’s still the dancing footman. He defines the periods when it would have been possible for the murderer to enter or leave the smoking-room.”

“Yes,” agreed Mandrake. “Thomas continued his antics until the music stopped, and that leaves a margin of a few minutes before Lady Hersey entered the room. The ‘boudoir’ is no good, because the door was still locked. I know that.”

“Then,” said Chloris slowly, “doesn’t it look as if the crucial time is the time when the murderer left the room? Because, whether he worked the wireless or not, he could only have got away after Thomas had left the hall.”

“Top marks for deduction, Miss Wynne,” said Alleyn.

“It’s a grim notion,” said Mandrake suddenly, “to think of us all sitting there calling for the news. If it was Hart, imagine him having to pull himself together and turn up the wireless!”

“Don’t,” said Chloris.

Alleyn had, with some difficulty in the jolting car, made a series of marginal notes. He now glanced up and found Chloris leaning her arm along the front seat and looking at him.

“I’d like to get Lady Hersey’s movements fixed in my head,” he said. “She went into the smoking-room with the drink, disappeared round the screen, returned to the doorway, said something you couldn’t hear, disappeared again, and called out to Mr. Royal, who then joined her. Finally she re-entered the library and asked you, Mandrake, to go to your host.”

“That’s it.” Mandrake changed down and crawled the car over its own skid marks. Chloris drew in her breath audibly. “It’s all right,” he said. “No trouble this time.” But Alleyn, who had been watching her, knew that it was not their progress that had scared her. She looked quickly at him and away again. “Lady Hersey,” she said, “is an old friend of the Complines. She’s terribly nice and she’s been absolutely marvellous since it happened. She was helping Dr. Hart with Mrs. Compline. She couldn’t be more sorry and upset about it all.”

These somewhat conventional phrases were shot out at nobody in particular and were followed by an odd little pause.

“Ah,” Alleyn murmured, “those are the sort of touches that help to clothe the bare bones of a case. We’ll collect some more, I hope, as we go along. I’m working backwards through your notes, Mandrake, and arrive at the booby-trap. A heavy brass Buddha, of all disagreeable objects, is perched on the top of a door, so that when the door is opened it is bound to fall on the person who pushes the door. The room is Nicholas Compline’s and it is upon his arm the Buddha falls. This trap was set, you say, during a visit Compline paid to Madame Lisse. You’ve worked out a time check on two clocks; the grandfather clock at the top of the stairs and the drawing-room clock which agrees with it. On this reckoning it appears that the trap was set some time between half-past seven, which struck as Nicholas Compline left his room, and a minute or so past twenty to eight, when you heard him cry out as the Buddha struck his arm. You suggest that you have found alibis during this period for everybody but Dr. Hart, who was in the bathroom. Lady Hersey gives Mrs. Compline her alibi, Mr. Royal gives you yours, Mandrake. Can you return the gesture?”

“I can say that I think he arrived in the drawing-room some little time before the crash.”