Rather conscience-stricken, the chums obeyed her suggestion. They were fortunate enough to slip from the kitchen-garden without being observed, and hoped their escapade would not be discovered. After tea they hurried to make up arrears of practising, but Gerda, evading the vigilance of Mademoiselle, gave an excuse to Miss Harding and absented herself from preparation. Stealing very cautiously from the house she dived through the shrubbery and ran out on to the warren. Casting many a hasty glance behind her to see if she were observed, she hurried along till she reached the little point above St. Perran's well where a rough pile of stones made a natural beacon, easily visible from the sea or from the beach below. Taking her handkerchief from her pocket she tied it to a stick, which she planted at the summit of the pile. Waving in the breeze it was a conspicuous object. She watched it for a moment or two, then walked back along the cliff with the drooping air of one who is almost ready to collapse after meeting a great emergency. "It was a near thing--a near thing!" she muttered to herself. "Suppose they'd met? Oh, it's too horrible! It was too risky an experiment, really! I hope my danger signal's plain enough. I must get up early to-morrow and take it down before anyone from the school sees it. It'll be difficult with those two in the room--but I'll manage it somehow. Fortunately they're both sound sleepers!" CHAPTER XVIII An Alarm That same evening an extraordinary thing happened. It was the custom for glasses of milk, dishes of stewed fruit, and plates of bread and butter to be placed on the table in the dining-hall about eight o'clock. This was done as usual, but when the girls arrived for supper they found a large proportion of the bread and butter had vanished. At first the suspicion fell on Spot, the fox-terrier, but the cook pleaded an alibi on his behalf, proving that he had been in the kitchen the whole time; also, the rifled plates were in the middle of the table, so no dog could have purloined their contents without knocking over glasses, or disturbing spoons and forks. "I'm afraid it's a two-legged dog," said Miss Harding gravely. "The French window was open, and it would be easy for anyone to walk in and help himself. I'm glad nothing more valuable was taken. I wish Miss Birks were here! It's most unfortunate it should happen on the very evening she's away."