In a few minutes she was ringing the bell of Number seven, Cornwallis Road, and almost immediately the door was opened by a butler.

"Miss Tregarth?" he guessed at once, for there was no mistaking her distress. "Professor Raxel told me to expect you."

"Where's my brother?"

The man threw open a door.

"If you will wait here, Miss Tregarth, I will tell the Professor that you have arrived."

She went in. The room was furnished as a waiting room, and she wondered what the professor's profession was. There were a couple of armchairs, a bookcase in one corner, and a table in the centre littered with magazines. She sat down and strove to possess herself in patience; but she had not long to wait.

In a few moments the door opened, and a tall, thin, elderly man entered. She sprang up.

"Are you Professor Raxel?"

"I am. And you, of course, are Miss Tregarth." He took her hand. "I am afraid you will not be able to see your brother for a few minutes, as the doctor is still with him, Please sit down again."

She sat down, struggling to preserve her composure.

"Tell me--what's happened to him?"

Before answering, the Professor produced a gold cigarette case and offered it. She would have refused, but he insisted.

"It doesn't take a professor to see that you are in a bad state of nerves," he said kindly. "A cigarette will help you."

She allowed him to light a cigarette for her, and then repeated her demand for information.

"It is difficult to tell you," said Raxel slowly, and suddenly she was terrified.

"Do you mean--"

He placed the tips of his fingers together.

"Not exactly," he said, "In fact, I have no doubt that your brother is in perfect health. I must confess, my dear Miss Tregarth, that I lured you here under false pretenses. I have not seen your brother this evening, but I have been told that he went out a little over an hour ago. There is no more reason to suppose that he has met with an accident to-night than there would be for assuming that he had met with one on any other night that he chose to go put alone."