"I can't help you," said Mrs Oliver. "I can't imagine who could have done it. At least, of course, I can imagine - I can imagine anything! That's the trouble with me. I can imagine things now - this minute. I could even make them sound all right, but of course none of them would be true. I mean, she could have been murdered by someone who just likes murdering girls but that's too easy - and, anyway, too much of a coincidence that somebody should be at this fete who wanted to murder a girl. And how would he know that Marlene was in the boathouse? Or she might have known some secret about somebody's love affairs, or she may have recognised somebody who was concealing his identity - or she may have known a secret about where some treasure was buried during the war. Or the man in the launch may have thrown somebody into the river and she saw it from the window of the boathouse - or she may even have got hold of some very important message in secret code and not known what it was herself."