“This is where I came out on my chase after Master Palmer,” explained Alleyn. “I met the P.C. in the street there. This door moves very sweetly.”

He flashed his torch on the hinges.

“Nicely oiled. Commendable attention to detail on the part of the staff—what?”

“Look here, Mr. Alleyn, what are you getting at?”

“I think we should concentrate on this door, Wade. When we’ve done here, we’ll go and have a look at the plan in the office and I shall propound my unlikely theory.”

He squatted on his heels and peered at the threshold.

“Not much chance here. Fine night and all that. I think it might be profitable to find out who oiled the hinges. Could you try? And the doorkeeper—Singleton is it? I suppose none of the guests went in twice? No, not Mason—anyone else.”

“Went in twice?”

“Yes. In at the stage-door. Out by this one. In again at the stage-door. Nothing in it, I dare say.”

“None of the guests has got a motive, though,” said Wade with a certain air of desperate reluctance.

“Not so far as we know. One might advance something rather fantastic. Young Palmer, mad for love, for instance. Far-fetched.”

“Well then—”

“And Gascoigne. He didn’t go to the dressing-rooms. He was on the stage. Have you dwelt on Gascoigne, Wade?”

“Thrashed him to death. We can’t get it down to what you might call a cast-iron alibi, sir, because he was mucking round on the stage here, but the hands say he never went off the set and we’ve found out he was there to welcome each of the guests as they came. No motive, far as we know.”

“And he would have no occasion to use this door.”

“This ‘in again, out again, gone again’ stuff with the door. Is it probable do you think, Mr. Alleyn? Is it possible?”

“Let’s consider. Take any one of the guests—young Palmer or Dr. Te Pokiha, for instance.”

“Go ahead, sir.”

“Young Palmer comes to the party, passes Singleton, gives his name, and instead of joining the party on the stage, slips round to the back and up the ladder. He takes off the weight, comes down, lets himself out by this door, shins round to the front, comes in again and joins the party.”

“I’m sure Singleton would have noticed it, Mr. Alleyn. You see, Mason had warned him about gate-crashing. He was on the look-out. He had the list of guests and he ticked each one off.”

“Yes, that’s the great objection,” agreed Alleyn. “Still, I’d ask him.”

“Certainly, we’ll ask him. The other objection is that the deceased was a stranger here, and most of the guests wouldn’t have the ghost of a motive. What about Mason, now? Could he have done this door business, after he went in with you?”