"And that was inside the chest too?"
"Yes. Wait a moment. After the noise Mrs. Pettigrew-Robinson heard, Mary woke up Freddy and then the Pettigrew-Robinsons—and then what?"
"She locked herself into her room."
"Yes. And shortly afterwards she came down and joined the others in the conservatory, and it was at this point everybody remembered noticing that she was wearing a cap and coat and walking shoes over pajamas and bare feet."
"You are suggesting," said Parker, "that Lady Mary was already awake and dressed at three o'clock, that she went out by the conservatory door with her suit-case, expecting to meet the—the murderer of her—damn it, Wimsey!"
"We needn't go so far as that," said Peter; "we decided that she didn't expect to find Cathcart dead."
"No. Well, she went, presumably to meet somebody."
"Shall we say, pro tem., she went to meet No. 10?" suggested Wimsey softly.
"I suppose we may as well say so. When she turned on the torch and saw the Duke stooping over Cathcart she thought—by Jove, Wimsey, I was right after all! When she said, 'You've killed him!' she meant No. 10—she thought it was No. 10's body."
"Of course!" cried Wimsey. "I'm a fool! Yes. Then she said, 'It's Denis—what has happened?' That's quite clear. And, meanwhile, what did she do with the suit-case?"