"We don't know the office."
"I'll find it," said Luther coolly, "if I hunt through every office of that sort in London. By the way, when you were in the house did you hear any one about?"
"No. Not a soul. And yet----" he hesitated.
"Who was singing while you talked to Mulligan?"
Arnold jumped up and shuddered. "Tracey, I declare that was the most horrible thing about the business. I don't know."
"Yet you were in the room."
"I was, and I saw the dead body, which I recognised as that of my cousin. I saw the policeman pass and repass out of the window. Then, thinking he was gone, I went out."
"Wait a bit. You told Miss Mason, that you saw him leaning over the gate? Don't make any mistake. This is important."
Arnold coloured. "I am telling you the exact truth. I was so confused over the whole business that I mix up things. I left the room before the singing commenced. I waited in the hall for ten minutes, hoping the policeman would not come back. Then I opened the door----"
"Hold on a shake. Why didn't you go up and see who was singing?"