"Well, look here, we must keep an eye on her, and next time we see her decamping we'll just follow her, and watch where she goes. I don't like people with underhand ways." "It doesn't suit us at the Dower House," agreed Dulcie. Though the chums kept Gerda's movements under strict surveillance for several days, they could discover nothing at which to take exception. She did not attempt to absent herself, or in any way break rules; she asked no questions, and exhibited no curiosity on any subject. If possible, she was even more silent and self-contained than before. Rather baffled, the girls nevertheless did not relax their vigilance. "She's foxing. We must wait and see what happens. Don't on any account let her humbug us," said Deirdre. One afternoon a strong west wind blowing straight from the sea seemed to promise such a good haul at their engrossing occupation that the girls, who for a day or two had forsaken salvaging in favour of hockey practice, turned their steps one and all towards the beach. As they walked along across the warren they had a tolerably clear and uninterrupted view of the whole of the little peninsula, and were themselves very conspicuous objects to anyone who chanced to be walking on the shore. Deirdre's eyes were wandering from sea to sky, from distant rock to near primrose clumps, when, happening to glance in the direction of the cliff that overtopped St. Perran's well, she was perfectly sure that she saw a white handkerchief waved in the breeze. It was gone in an instant, and there was no sign of a human figure to account for the circumstance, but Deirdre was certain it was no illusion. She called Dulcie's attention to it, but Dulcie had been looking the other way, and had seen nothing. "Probably it was only a piece of paper blowing down the cliff," she objected. "How could it be anyone waving? Nobody's allowed on the warren." "It might be Ronnie and Miss Herbert." "Oh no! We could see them quite plainly if it were." "Gerda, did you notice something white?" "I don't see anything there," replied Gerda, surveying the distance with her usual inscrutable expression. "I think you must have been mistaken." It seemed quite a small and trivial matter, and though Deirdre, for the mere sake of argument, stuck to her point all the way down to the beach, the others only laughed at her. "You'll be saying it's a ghost next," declared Betty. "I think you're blessed with a very powerful imagination, Deirdre."