Nevertheless, his conscience pricked him slightly. The emerald ought to be returned to the Rajah. He conceived the idea that he might perhaps do a little detective work—once, that is, that he had regained his own trousers and replaced the others. In pursuance of this idea, he directed his steps towards the aged mariner, whom he rightly regarded as being an exhaustible source of Kimpton information.

‘Excuse me!’ said James politely; ‘but I belive a friend of mine has a hut on this beach, Mr Charles Lampton. It is called Mon Desir, I fancy.’

The aged mariner was sitting very squarely in a chair, a pipe in his mouth, gazing out to sea. He shifted his pipe a little, and replied without removing his gaze from the horizon:

‘Mon Desir belongs to his lordship, Lord Edward Campion, everyone knows that. I never heard of Mr Charles Lampton, he must be a newcomer.’

‘Thank you,’ said James, and withdrew.

The information staggered him. Surely the Rajah could not himself have slipped the stone into the pocket and forgotten it. James shook his head, the theory did not satisfy him, but evidently some member of the house-party must be the thief. The situation reminded James of some of his favourite works of fiction.

Nevertheless, his own purpose remained unaltered. All fell out easily enough. The beach was, as he hoped it would be, practically deserted. More fortunate still, the door of Mon Desir remained ajar. To slip in was the work of a moment, Edward was just lifting his own trousers from the hook, when a voice behind him made him spin round suddenly.

‘So I have caught you, my man!’ said the voice.

James stared open-mouthed. In the doorway of Mon Desir stood a stranger; a well-dressed man of about forty years of age, his face keen and hawk-like.

‘So I have caught you!’ the stranger repeated.

‘Who—who are you?’ stammered James.

‘Detective-Inspector Merrilees from the Yard,’ said the other crisply. ‘And I will trouble you to hand over that emerald.’

‘The—the emerald?’

James was seeking to gain time.

‘That’s what I said, didn’t I?’ said Inspector Merrilees.

He had a crisp, business-like enunciation. James tried to pull himself together.

‘I don’t know what you are talking about,’ he said with an assumption of dignity.

‘Oh, yes, my lad, I think you do.’

‘The whole thing,’ said James, ‘is a mistake. I can explain it quite easily—’ He paused.

A look of weariness had settled on the face of the other.

‘They always say that,’ murmured the Scotland Yard man dryly. ‘I suppose you picked it up as you were strolling along the beach, eh? That is the sort of explanation.’

It did indeed bear a resemblance to it, James recognized the fact, but still he tried to gain time.

‘How do I know you are what you say you are?’ he demanded weakly.