‘No, I don’t. She’s turned the tables on me with a vengeance. I don’t like admitting, George, that a woman’s been too clever for us. It goes against the grain. But it’s true. We shan’t be able to prove anything against her, and yet we both know that she’s been the prime mover in the affair.’

‘Women are the devil,’ said Carrington with feeling.

‘Nothing to connect her with it, damn it all! We may believe that she put the girl up to that screaming trick, and that the man lurking outside was her accomplice, but the devil of it is we can’t prove it.’

‘Perhaps Hercule Poirot can.’

Suddenly Lord Mayfield laughed.

‘By the Lord, George, I thought you were too much of an old John Bull to put your trust in a Frenchman, however clever.’

‘He’s not even a Frenchman, he’s a Belgian,’ said Sir George in a rather shamefaced manner.

‘Well, have your Belgian down. Let him try his wits on this business. I’ll bet he can’t make more of it than we can.’

Without replying, Sir George stretched a hand to the telephone.

Blinking a little, Hercule Poirot turned his head from one man to the other. Very delicately he smothered a yawn.

It was half-past two in the morning. He had been roused from sleep and rushed down through the darkness in a big Rolls-Royce. Now he had just finished hearing what the two men had to tell him.

‘Those are the facts, M. Poirot,’ said Lord Mayfield.

He leaned back in his chair, and slowly fixed his monocle in one eye. Through it a shrewd, pale-blue eye watched Poirot attentively. Besides being shrewd the eye was definitely sceptical. Poirot cast a swift glance at Sir George Carrington.

That gentleman was leaning forward with an expression of almost childlike hopefulness on his face.

Poirot said slowly:

‘I have the facts, yes. The maid screams, the secretary goes out, the nameless watcher comes in, the plans are there on top of the desk, he snatches them up and goes. The facts—they are all very convenient.’

Something in the way he uttered the last phrase seemed to attract Lord Mayfield’s attention. He sat up a little straighter, his monocle dropped. It was as though a new alertness came to him.

‘I beg your pardon, M. Poirot?’

‘I said, Lord Mayfield, that the facts were all very convenient—for the thief. By the way, you are sure it was a man you saw?’

Lord Mayfield shook his head.

‘That I couldn’t say. It was just a—shadow. In fact, I was almost doubtful if I had seen anyone.’

Poirot transferred his gaze to the Air Marshal.

‘And you, Sir George? Could you say if it was a man or a woman?’

‘I didn’t see anyone myself.’

Poirot nodded thoughtfully. Then he skipped suddenly to his feet and went over to the writing-table.