“That’s right, sir. But it won’t wash as far as he is concerned. If Mason had gone through the audience, out at the front, and round the block, he’d have had to come in here. He would have to go aloft, do the job, come down, and sprint round the block again.”

“Ten minutes at the very least and the risk of being seen running like a madman by any number of people on the pavement outside,” said Alleyn. “No. That cat won’t jump. I saw the door last night when your P.C. was so suspicious of my movements. Have you got a torch? Let’s have a good look at it.”

By the light of both their torches they inspected the door.

“Yale lock, with the key inside,” said Alleyn.

“We noted this door last night, Mr. Alleyn. It wasn’t overlooked.”

“My dear chap, I’m sure it wasn’t. What did you make of it?”

“Well, seeing it was locked on the inside it doesn’t look as though anyone could have used it for an entrance. And seeing that there’s no exit from the dressing-rooms except to the stage, none of them could have used it for a getaway.”

“None of the cast, no.”

“You’re still thinking of Mason. It’s no go, sir. I wish to hell I could say otherwise, but it’s no go. We’ve thrashed it over—every minute of it—every second of it. He was in the office at the end of the show, and was seen there by the men from the box-office. He ran along to the stage-door and gave old Singleton—the doorkeeper—the message about not letting in uninvited people. Singleton watched him go back to the office and a minute or two later joined him there. Then Dr. Te Pokiha looked in. About two minutes later you overtook him yourself, on the way to the stage-door with the doctor.”

“Not with Dr. Te Pokiha. He was at the party when Mr. Mason and I got in.”

“Makes no odds, as far as Mason is concerned, sir.”

“That’s true. Have you tried this key for prints?”

“Can’t say we have.”

“It’s early days yet,” murmured Alleyn, “and you’ve had a lot of stuff to get through. I think if you don’t mind—”

He produced an insufflater and a packet of chalk from his overcoat pocket, and by the light of their torches, tested the key for prints.

“None. It’s as clean as a whistle.”

“That’s funny,” said Wade, reluctantly. “You’d have thought it would be used fairly frequently.”

“There’s no dust,” said Alleyn, “so presumably it has been wiped clean.”

Wade muttered something under his breath. Alleyn turned the key and opened the door. Outside was a dingy strip of yard, and a low tin fence with a rickety gate.