Suddenly he jumped up, his face alight. “Bill, I’ve got it!” he cried.

“What?”

“The shadow on the wall! I was looking at the shadow on the wall. Oh, ass, and ten times ass!”

Bill looked uncomprehendingly at him. Antony took his arm and pointed to the wall of the passage.

“Look at the sunlight on it,” he said. “That’s because you’ve left the door of that room open. The sun comes straight in through the windows. Now, I’m going to shut the door. Look! D’you see how the shadow moves across? That’s what I saw⁠—the shadow moving across as the door shut behind him. Bill, go in and shut the door behind you⁠—quite naturally. Quick!”

Bill went out and Antony knelt, watching eagerly.

“I thought so!” he cried. “I knew it couldn’t have been that.”