Margaret Barrimore turned her head and for the first time looked at her husband. Her expression, one of profound astonishment, was reflected in her son’s face and Dr Maine’s.

‘There is no doubt, I think,’ Alleyn said. ‘That during her first visit to the Island their relationship, however brief, had been of the sort to give rise to the later reaction.’

‘Is this true?’ Dr Maine demanded of Barrimore.

He had the towel clapped to his face. Over the top of it his eyes, prominent and dazed, narrowed as if he were smiling. He said nothing.

‘Miss Cost, as I said just now, kept her knowledge to herself. Later, it appears, she transferred her attention to Doctor Maine and was unsuccessful. It’s a painful and distressing story and I shan’t dwell on it except to say that up to yesterday’s tragedy we have the picture of a neurotic who has discovered that the man upon whom her fantasy is now concentrated, is deeply attached to the wife of the man with whom she herself had a brief affair that ended in humiliation. She also knows that this wife impersonated the Green Lady in the original episode. These elements are so bound up together, that if she makes mischief, as her demon urges her to do, she will be obliged to expose the truth about the Green Lady and that would be disastrous. Add to this, the proposal to end all publicity and official recognition of the Spring and you get some idea, perhaps, of the emotional turmoil that she suffered and that declares itself in this unhappy diary.’

‘You do, indeed,’ said Miss Emily abruptly and added: ‘One has much to answer for, I perceive. I have much to answer for. Go on.’

‘In opposing the new plans for the Spring, Miss Cost may have let off a head of emotional steam. She sent anonymous messages to Miss Pride. She was drawn into the companionship of the general front made against Miss Pride’s intentions. I think there is little doubt that she conspired with Trehern and egged-on ill feeling in the village. She had received attention. She had her Festival in hand. She was somebody. It was, I daresay, all rather exciting and gratifying. Wouldn’t you think so?’ he asked Dr Maine.

‘I’m not a psychiatrist,’ he said. ‘But, yes. You may be right.’

‘Now this was the picture,’ Alleyn went on, ‘up to the time of the Festival. But when she came to write the final entry in her diary, which was last night, something had happened: something that revived all her sense of injury and spite, something that led her to write: ‘Both – all of them – shall suffer. I’ll drag their names through the papers. Now. Tonight. I am determined. It is the end’.’

Another formidable onslaught roared down upon The Boy-and-Lobster and again the lights wavered and recovered.