‘Really, I didn’t notice.’

Carlile’s voice was repressive.

‘Aha, you did not notice? But you are a young man. Does not a young man notice when a girl is pretty?’

‘Really, M. Poirot, I can only repeat that I did not do so.’

Carlile cast an agonized glance at his employer. Sir George Carrington gave a sudden chuckle.

‘M. Poirot seems determined to make you out a gay dog, Carlile,’ he remarked.

‘Me, I always notice when a girl is pretty,’ announced Poirot as he descended the stairs.

The silence with which Mr Carlile greeted this remark was somewhat pointed. Poirot went on:

‘And it was then she told this tale of having seen a ghost?’

‘Yes.’

‘Did you believe the story?’

‘Well, hardly, M. Poirot!’

‘I do not mean, do you believe in ghosts. I mean, did it strike you that the girl herself really thought she had seen something?’

‘Oh, as to that, I couldn’t say. She was certainly breathing fast and seemed upset.’

‘You did not see or hear anything of her mistress?’

‘Yes, as a matter of fact I did. She came out of her room in the gallery above and called, “Leonie.”’

‘And then?’

‘The girl ran up to her and I went back to the study.’

‘Whilst you were standing at the foot of the stairs here, could anyone have entered the study by the door you had left open?’

Carlile shook his head.

‘Not without passing me. The study door is at the end of the passage, as you see.’

Poirot nodded thoughtfully. Mr Carlile went on in his careful, precise voice.

‘I may say that I am very thankful that Lord Mayfield actually saw the thief leaving the window. Otherwise I myself should be in a very unpleasant position.’

‘Nonsense, my dear Carlile,’ broke in Lord Mayfield impatiently. ‘No suspicion could possibly attach to you.’

‘It is very kind of you to say so, Lord Mayfield, but facts are facts, and I can quite see that it looks badly for me. In any case I hope that my belongings and myself may be searched.’

‘Nonsense, my dear fellow,’ said Mayfield.

Poirot murmured:

‘You are serious in wishing that?’

‘I should infinitely prefer it.’

Poirot looked at him thoughtfully for a minute or two and murmured, ‘I see.’

Then he asked:

‘Where is Mrs Vanderlyn’s room situated in regard to the study?’

‘It is directly over it.’

‘With a window looking out over the terrace?’

‘Yes.’

Again Poirot nodded. Then he said:

‘Let us go to the drawing-room.’

Here he wandered round the room, examined the fastenings of the windows, glanced at the scorers on the bridge table and then finally addressed Lord Mayfield.

‘This affair,’ he said, ‘is more complicated than it appears. But one thing is quite certain. The stolen plans have not left this house.’

Lord Mayfield stared at him.

‘But, my dear M. Poirot, the man I saw leaving the study—’

‘There was no man.’

‘But I saw him—’