‘I’m not suggesting that anything like that happened,’ said Inspector Bland, ‘but you must realize, Sir George, that in looking for the murderer of Marlene Tucker the field is a more restricted one than one might think at first.’

‘Restricted!’ Sir George stared. ‘You’ve got the whole ruddy fête to choose from, haven’t you? Two hundred – three hundred – people? Any one of ’em might have done it.’

‘Yes, I thought so at first, but from what I’ve learnt now that’s hardly so. The boathouse door has a Yale lock. Nobody could come in from outside without a key.’

‘Well, there were three keys.’

‘Exactly. One key was the final clue in this Murder Hunt. It is still concealed in the hydrangea walk at the very top of the garden. The second key was in the possession of Mrs Oliver, the organizer of the Murder Hunt. Where is the third key, Sir George?’

‘It ought to be in the drawer of that desk where you’re sitting. No, the right-hand one with a lot of the other estate duplicates.’

He came over and rummaged in the drawer.

‘Yes. Here it is all right.’

‘Then you see,’ said Inspector Bland, ‘what that means? The only people who could have got into the boathouse were first, the person who had completed the Murder Hunt and found the key (which as far as we know, did not happen). Second, Mrs Oliver or some member of the household to whom she may have lent her key, and, third, someone whom Marlene herself admitted to the room.’

‘Well, that latter point covers pretty well everyone, doesn’t it?’

‘Very far from it,’ said Inspector Bland. ‘If I understand the arrangement of this Murder Hunt correctly, when the girl heard anyone approaching the door she was to lie down and enact the part of the Victim, and wait to be discovered by the person who had found the last clue – the key. Therefore, as you must see for yourself, the only people whom she would have admitted, had they called to her from outside and asked her to do so, were the people who had actually arranged the Murder Hunt. Any inmate, that is, of this house – that is to say, yourself, Lady Stubbs, Miss Brewis, Mrs Oliver – possibly M. Poirot whom I believe she had met this morning. Who else, Sir George?’

Sir George considered for a moment or two.

‘The Legges, of course,’ he said. ‘Alec and Sally Legge. They’ve been in it from the start. And Michael Weyman, he’s an architect staying here in the house to design a tennis pavilion. And Warburton, the Mastertons – oh, and Mrs Folliat of course.’

‘That is all – nobody else?’

‘That’s the lot.’

‘So you see, Sir George, it is not a very wide field.’

Sir George’s face went scarlet.

‘I think you’re talking nonsense – absolute nonsense! Are you suggesting – what you are suggesting?’