"That you will discover," said he.

"I am not asking out of idle curiosity, but I want to know whether I ought to take a bag."

"Perhaps it would be better," he said.

She carried the little attache case back to the sitting-room.

"You have no objection to my taking a little light reading-matter?" she asked contemptuously. "I am afraid you are not a very entertaining companion, Dr. van Heerden."

"Excellent girl," said van Heerden cheerfully. "Take anything you like."

She slipped a book from the shelf and nearly betrayed herself by an involuntary exclamation as she felt its weight.

"You are not very original in your methods," she said, "this is the second time you have spirited me off."

"The gaols of England, as your new-found friend Milsom will tell you, are filled with criminals who departed from the beaten tracks," said van Heerden. "Walk out into the corridor and turn to the right. I will be close behind you. A little way along you will discover a narrow passage which leads to the service staircase. Go down that. I am sure you believe me when I say that I will kill you if you attempt to make any signal or scream or appeal for help."

She did not answer. It was because of this knowledge and this fear, which was part of her youthful equipment--for violent death is a very terrible prospect to the young and the healthy--that she obeyed him at all.

They walked down the stone stairs, through an untidy, low-roofed lobby, redolent of cooking food, into the street, without challenge and without attracting undue notice.

Van Heerden's car was waiting at the end of the street, and she thought she recognized the chauffeur as Bridgers.

"Once more we ride together," said van Heerden gaily, "and what will be the end of this adventure for you depends entirely upon your loyalty--what are you opening your bag for?" he asked, peering in the dark.

"I am looking for a handkerchief," said Oliva. "I am afraid I am going to cry!"

He settled himself back in the corner of the car with a sigh of resignation, accepting her explanation--sarcasm was wholly wasted on van Heerden.

"Well, gentlemen," said Milsom, "I don't think there's anything more I can tell you. What are you going to do with me?"

"I'll take the responsibility of not executing the warrant," said McNorton. "You will accompany one of my men to his home to-night and you will be under police supervision."

"That's no new experience," said Milsom, "there's only one piece of advice I want to give you."

"And that is?" asked Beale.

"Don't underrate van Heerden. You have no conception of his nerve. There isn't a man of us here," he said, "whose insurance rate wouldn't go up to ninety per cent. if van Heerden decided to get him. I don't profess that I can help you to explain his strange conduct to-day. I can only outline the psychology of it, but how and where he has hidden his code and what circumstances prevent its recovery, is known only to van Heerden."

He nodded to the little group, and accompanied by McNorton left the room.

"There goes a pretty bad man," said Kitson, "or I am no judge of character. He's an old lag, isn't he?"

Beale nodded.

"Murder," he said laconically. "He lived after his time. He should have been a contemporary of the Borgias."

"A poisoner!" shuddered one of the under-secretaries. "I remember the case. He killed his nephew and defended himself on the plea that the youth was a degenerate, as he undoubtedly was."

"He might have got that defence past in America or France," said Beale, "but unfortunately there was a business end to the matter. He was the sole heir of his nephew's considerable fortune, and a jury from the Society of Eugenics would have convicted him on that."

He looked at his watch and turned his eyes to Kitson.

"I presume Miss Cresswell is bored and has retired for the night," he said.

"I'll find out in a moment," said Kitson. "Did you speak to her?"

Beale nodded, and his eyes twinkled.

"Did you make any progress?"

"I broke the sad news to her, if that's what you mean."

"You told her she was married to you? Good heavens! What did she say?"

"Well, she didn't faint, I don't think she's the fainting kind. She is cursed with a sense of humour, and refused even to take a tragic view."

"That's bad," said Kitson, shaking his head. "A sense of humour is out of place in a divorce court, and that is where your little romance is going to end, my friend."

"I am not so sure," said Beale calmly, and the other stared at him.

"You have promised me," he began, with a note of acerbity in his voice.

"And you have advised me," said Beale.

Kitson choked down something which he was going to say, but which he evidently thought was better left unsaid.

"Wait," he commanded, "I will find out whether Miss Cresswell," he emphasized the words, "has gone to bed."

He passed through the door to Oliva's sitting-room and was gone a few minutes. When he came back Beale saw his troubled face, and ran forward to meet him.

"She's not there," said Kitson.

"Not in her room?"

"Neither in the sitting-room nor the bedroom. I have rung for her maid.

Oh, here you are."

Prim Minnie came through the bedroom door.

"Where is your mistress?"

"I thought she was with you, sir."

"What is this?" said Beale, stooped and picked up a white kid glove.

"She surely hasn't gone out," he said in consternation.