“Quite so. The manager, George Mason, came to the stage-door and repeated, gratuitously, and un-nesh—unessessraly, my instructions. I was to be sure to ask of each guest his local habitation and his name.

“Mr. Mason returned to the office?”

“I swear it.”

“You may have to,” said Alleyn. “How long was Mr. Mason away from the office?”

“Let me see. Let me see. While one with moderate haste might tell an hundred. I showed him my list. I convinced him of my incorruptible purpose. I called to mind, I recollect, the coincidence that I had played the part of the porter in Macbeth, and of the sentry, Bernardo, in the Dane—that was in my green and salad days, Commissioner. I had scarce embarked on this trifling reminiscence when Mason turned up the collar of his dinner-jacket and observing that the air was chilly, turned and ran back to the office.”

Alleyn uttered a slight exclamation, glanced at Wade, and asked Singleton to repeat this statement, which he did at great length but to the same effect.

“Do you remember, now,” said Alleyn, “if the office door was open on to the yard as it is now?”

“It was open.”

“Ah yes. You know Dr. Te Pokiha by sight?”

“The native? Dark-visaged, like the Moor? The Moor was perhaps my greatest role. My favourite role. ‘Most potent grave—’”

“Wonderful play, that,” interrupted Alleyn. “Dr. Te Pokiha was among the last guests to arrive, I think?”

“True.”

“Did you notice him coming?”

“I marked him come, yes. He too emerged from the office, carrying his mantle. He darted back and reappeared. He approached me and I admitted him, striking out his name as I did so.”

“Now, Mr. Singleton, I take it from what you have told me that you would be prepared to make a sworn statement that once Mr. Ackroyd, or Mr. Mason, or Dr. Te Pokiha had gone in at the stage-door they did not return to the office, and once they had gone to the office, did not return to the stage without your knowledge?”

“I have sworn it, indeed. In common parlance, sir, you can bet your boots and put your shirt on it.”

“Well now, Mr. Singleton, I’m going to ask you to help me in a little experiment. Will you do this?”

“Impart! Proceed!”

“I want you to stand here by the stage-door and treat me as though I was Mr. Ackroyd, Dr. Te Pokiha, or Mr. Mason. As soon as I have gone, I want you to wait for five minutes and then walk along to the office. Will you do this?”

“Certainly.”

“Watch the office door,” said Alleyn, “and Mr. Wade will keep the time.” He glanced at Packer and Cass who had listened to the entire conversation with the liveliest interest. “You look steadily down the alley, you two. Are you keen on conjuring tricks?”

“I remember—” began Mr. Singleton; but Alleyn interrupted him.