After the delightful dissipation of a whole day's holiday, Miss Birks demanded a period of solid work from her pupils, and deeming that she had sufficiently satisfied their craving for excitement, took no notice of either hints or headaches, but enforced preparation and practising with, as Dulcie expressed it, "a total lack of all consideration". Dulcie, never a remarkably hard worker at any season, was more than usually prone to "slack" in summer, and it needed the combined energies of Miss Birks, Miss Harding, and Mademoiselle to keep her up to the mark. It was more than ever necessary to maintain the standard at present, for examination week was drawing near, and this year several extra prizes were offered for competition. Mrs. Trevellyan had promised a beautiful edition of Tennyson's poems for the best paper on English literature, the Vicar added a handsome volume of Pictures from Palestine for the most correct answers to Scripture History, and Mademoiselle herself proffered a copy of Lettres de mon Moulin for the most spirited declamation of any piece of French poetry not less than two hundred lines in length, the quality of the accent to be particularly taken into account. These were in addition to the usual annual rewards for mathematics, languages, English history, music, drawing, and needlecraft, so that among so many various subjects each girl might feel that she had at least some chance of winning success. At the eleventh hour the Principal announced that a prize would be given for general improvement.

"That's to make slackers like you buck up, Dulcie!" declared Annie Pridwell.

"Really, I wish Miss Birks would offer a prize for pure English," said Jessie Macpherson, who happened to overhear. "The slang you Vb talk is outrageous. Your whole conversation seems made up of 'ripping' and 'scrumptious' and 'spiffing' and other silly words that don't mean anything. I tell you, slang's going out of fashion, even at public schools, and you're behind the times."

"Don't be a prig, Jessie. What else can I call Dulcie except a slacker? Am I to say she shows a languorous disinclination for close application, and advise her to exert her mental activities? It would sound like a 'Catechism' from a Young Ladies' Seminary of a hundred years ago!"

"There is one comfort in having worked badly," admitted Dulcie. "If I make a spurt now, I shall show more 'marked improvement' than if I'd been jogging along steadily all the time." "Ah, but the tortoise won the race while the hare slept!" retorted Jessie.

In view of the forthcoming music examination, practising was performed with double diligence, and from 6 a.m. to 8.30 p.m. the strains of Schumann's "Arabesque", Tschaikowsky's "Chanson Triste", or Rachmaninoff's "Prelude", the three test pieces, echoed pretty constantly through the house, in varying degrees of proficiency.

"It's a good thing nobody belonging to the school has to do the judging," said Emily Northwood, as she stood in the hall listening to the conflicting sounds of three pianos. "Even Miss Birks must be so sick of these particular pieces that she could hardly express a fair opinion on them. Dr. Harvey James will come fresh to the fray."

The organist and choirmaster of the collegiate church at Wexminster, being a doctor of music, was regarded as a very suitable examiner for the occasion, and even if his standard proved high, all at least would have the same chance, for he had not visited the school before, and therefore could regard nobody with special favour. He was a new resident in the district, and Miss Birks hoped next term to arrange for him to come over weekly and give lessons to her more advanced pupils, who would be likely to appreciate his musical knowledge and profit by his teaching.

The thought of having to play before their prospective music master spurred on most of the girls even more than the chance of the prize; they dashed valiantly at difficult passages, counted diligently, and loosened their muscles with five-finger exercises, each anxious to be placed in the rank of those sufficiently advanced to be transferred to his tuition. The drawing students also, though they could not practise specially for their own prize, were busy finishing copies and sketches for a small exhibition of work done during the school year, which was to be held in one of the classrooms during examination week, and criticized by Mr. Leonard Pearce, an artist who had consented to set and judge the competition. Miss Harding was urging increased attention to mathematics, Miss Birks was giving extra coaching in history and English literature, Mademoiselle was hacking away at languages till her pupils almost wished that French and German were as dead as ancient Egyptian and Assyrian, so it was a very busy little world at the Dower House, so busy that really nobody had time to think of anything else. The Principal, anxious to keep her flock in good health, insisted upon the recreation hours being devoted to definite exercise, and either games or organized walks under the supervision of a mistress were compulsory.

For the present there was no strolling about the warren in "threesomes", there were no visits to the headland, or rambles on the beach. The girls grumbled a little at this lack of their accustomed freedom, complained that set walks reminded them of a penitentiary, and declared that to be obliged to play cricket took all the fun out of it. They thrived on the system, however, and were able to manage the increased brain work demanded from them without incurring the penalty of headaches, backaches, or loss of appetite. A few certainly pleaded minor ailments as an excuse for shirking, but Miss Birks's long experience had taught her to distinguish readily between real illness and shamming, and she dismissed the would-be invalids each with a dose of such a nauseous compound as entirely to discourage them from seeking further sympathy. Her bottle, a harmless mixture of Turkey rhubarb and carbonate of magnesia, might have been a magic elixir for the relief of all diseases, for with the same marvellous rapidity it cured Francie's palpitations, Irene's dyspepsia, and Elyned's attacks of faintness.

"Nasty, filthy stuff!" declared the indignant sufferers, who, with a remembrance of Miss Birks's treatment of the measles patients, had fondly expected to be coddled and cosseted, regaled on soda-water and lemonade, and forbidden to overexert themselves.

"Serve you right!" chuckled their friends. "It's your own faults, for you couldn't expect Miss Birks to believe in your whines when you look in such absolutely rude health, and compass your meals so creditably. Why didn't you refuse all solid food?" "Oh no, thank you!"

"And declare cocoa made you shudder?"

"That's beyond a joke."

"If anybody looks ill in this house," continued Annie, "it's Mademoiselle. She's pale and thin, if you like, and eats next to nothing, but she doesn't make any fuss about it."

Noticeably Mademoiselle's increased work and anxiety on behalf of her pupils' success had a bad effect on her health. She looked worn and overdone, and there were dark circles round her tired eyes. Though she did not complain, she confessed to being troubled with sleeplessness. Night after night she lay awake till daybreak, and was sometimes only dropping into a doze when the getting-up bell clanged in the passage. "Nuits blanches may be all very well in music, but they are not pleasant when one experiences them," she confided to Miss Harding. "When I stay waiting for sleep, I hear many curious sounds. Yes—such as one does not hear during the daylight."

"A house is always full of creaks and groans if one stays awake at night," returned Miss Harding. "You mustn't mind them."

"During the day I smile at them," continued Mademoiselle, "but if I keep vigil I am nervous. Yes, to-night I shall be very nervous, for Miss Birks will be away. I like not that she be away."

It was very seldom that the Principal gave herself a holiday during the term, but for once she was going to London to attend an important educational meeting, and would spend the night in town. She started by an early train, leaving her small kingdom in perfect order, and confident that for so short a space of time nothing could possibly go wrong. Certainly nothing ought to have gone wrong; her arrangements were excellent, and Miss Harding was thoroughly capable of acting deputy during her absence. Yet there is an old proverb that "while the cat's away the mice will play", and the mere fact that she was not on the spot made a difference in the school. The girls did not give any trouble, but there was a feeling of relaxed discipline in the air.

At four o'clock, instead of going straight from their classroom to their practising, Deirdre and Dulcie decided to indulge in the luxury of a run round the grounds first. They walked briskly through the shrubbery, down the steps, and along the terrace, till they came to the kitchen-garden. Now this kitchen-garden was absolutely forbidden territory to the girls, and they had never been inside it. To-day the gate, which was generally locked, stood temptingly open. It seemed an opportunity too good to be resisted. With one accord they threw rules to the winds, and decided to explore.

A thick and high holly hedge effectually screened this corner of the grounds from wind, and guarded it from intruders. It was a warm, productive plot of land, and entirely provided the school with fruit and vegetables. Deirdre and Dulcie did not trouble about the currants and gooseberries, but kept straight down the path. They wished particularly to investigate the far end. Here the garden abutted on the cliffs, which sloped downward in a series of zigzag ridges.

The girls made their way gingerly over a freshly-prepared bed of young cabbages to the borderland where rhubarb and horse-radish merged into wormwood and ragwort. It was perfectly easy to slip over the edge and begin to go down the first long shelving slab of rock. There was a drop of about four feet on to the second shelf, which again sloped downwards at a gentle level to a third. Here the cliff ended in a precipice, so steep that even the most experienced climber could not descend without a rope. Rather baffled, the two girls crept cautiously along the edge, then Deirdre suddenly gave a whoop of delight, for she had spied a rough flight of steps cut in the surface of the rock, and evidently leading to the beach below. It was rather a cat's staircase to venture upon, but they were possessed with a thirst for exploration, and were not easily to be daunted. Deirdre went first, and shouted encouragement to her chum, and Dulcie picked up heart to follow, so that in the course of a few minutes they found themselves safely on the sands at the bottom.

"Whew! It's like climbing down the ladder of a lighthouse," exclaimed Dulcie, subsiding on to a convenient stone. Her legs were shaking in a most unaccountable fashion, and her breath coming and going far more rapidly than was comfortable.

"It might have been worse," affirmed Deirdre, trying not to show that her nerve had in any degree failed her, and surveying the scene with the eye of a prospector.

They were in a small and very narrow cove, so hidden between cliffs which jutted out overhead that it was practically invisible from above, and certainly could not be seen from anywhere in the school grounds. It was a pretty little creek, with a silvery slip of beach, and green clumps of ferns growing high up in the interstices of the rocks; quite a romantic spot, so beautiful and secluded that it might almost be the haunt of a mermaiden or a water nixie. The ferns, which were flourishing in unusual luxuriance, caught Deirdre's attention.

"I believe it's the sea-spleenwort," she remarked. "Don't you remember we found some at Kergoff, and Miss Birks was so excited about it? I'm sure she doesn't know all this is growing at the very bottom of her own garden. I'll try and get a root."

To obtain a root was more easily said than done, however. Most of the clumps of fern were in very inaccessible situations, and too deeply embedded in the rock to be removed. Deirdre climbed from one to another in vain, then noticing a particularly fine group of fronds on a projecting shelf far above her head, commenced to scale the cliff. She reached the shelf fairly easily, but instead of setting to work to try to uproot the fern, she gave a long whistle of surprise.

"What's the matter?" asked Dulcie from below.

"Matter! Come up yourself and see! Oh, goody!"

Dulcie was still a little shaky, but spurred on by curiosity she got up the cliff somehow, and added a "Hallo!" of amazement to her chum's exclamations. Facing them was the entrance to a cave. At one time it had evidently been carefully blocked up, but now the wooden boarding that guarded it had been wrenched asunder, leaving a small opening just sufficient to enter by. The girls peeped cautiously in, but beyond the first few yards all was dark. This was indeed a discovery. The mouth of the cave was so effectually hidden by the crags which surrounded it that nobody would have suspected its existence who had not come across it by accident. What secrets lay in its mysterious depths, who could say? Thrilled with excitement, the girls turned to one another.

"If we could only explore it!" breathed Dulcie.

"We're going to!" returned Deirdre firmly. "I shall run back this instant to the house for a candle. You wait here."

Deirdre's impatience made short work of the cat's staircase. She scrambled up the rocks like a squirrel, and was soon racing up the kitchen-garden. To secure her bedroom candle and a box of matches was the work of a few minutes. As she pelted impetuously downstairs again, she nearly fell over Gerda, who had been doing preparation in the schoolroom, and scattered the pile of books she was carrying.

"Do be careful," said the latter in remonstrance. "Where are you going in such a hurry? And what do you want with your candle?"

"Never you mind! It's no business of yours!" retorted Deirdre, running away without even an apology.

Gerda picked up her books and carried them upstairs, but instead of continuing her preparation she went to the window. She was just in time to catch a glimpse of Deirdre vanishing down the kitchen-garden. The sight seemed to afford her food for thought. She stood for a moment or two lost in indecision, then, evidently making up her mind, she set off in pursuit of her school-fellow. Deirdre, meanwhile, returned to the cove with speed and agility, and found Dulcie waiting where she had left her.

"I had a horrible feeling that a monster might come out while you were away!" she declared. "Do you think we dare go in?"

"Dare? Of course we dare! I'm not going to have fetched this candle for nothing. Dulcie Wilcox, where's your pluck? Come along this minute, or I'll not be chums with you again. Here, you may hold the matches." Having lighted the candle, the two girls stepped through the breach in the wooden barricade, and commenced their exploration. The passage, high at first, soon lowered till it was little above their heads, and narrowed to a width of barely three feet. The walls, which for the first ten yards were worn as if by the action of the sea, became more jagged, and had plainly been hewn out with the aid of a pick, the natural cavern having been greatly extended. Here and there the floor was wet, and the roof showed an oozy deposit as if some surface spring were forcing itself through the strata of the rock. On and on the girls went for two hundred yards or more, Deirdre going first and holding the candle well in front of her, so as to see the way. It was delightfully exciting, yet there was a thrill of horror about it, for who could tell what might be lurking round the next corner? Dulcie's nerves were strung to such a pitch that she was ready to scream at the least alarm. Not a sound, however, broke the dead silence. The passage in its lonely calm might have been the entrance to an Egyptian tomb.

"Does it lead anywhere?" whispered Dulcie. "Oh! hadn't we better turn back? We've gone far enough."

"I'm going to the end, if it's in Australia!" replied Deirdre, and having possession of the candle, she was in a position to dictate.

A few extra yards, however, concluded their journey, the passage being once again blocked by a wooden barrier. This was more carefully constructed than the one at the entrance, being made of well-planed timber, and fitted with a door, which stood half-way open, and led into a rough kind of chamber, rather resembling the crypt of a church. At the far side of this there was a small closed door.

"Well, we've got into a queer place!" exclaimed Deirdre. "Must have been a smuggler's cellar, I should say. No doubt they used to keep kegs and kegs of brandy down here in the good old days. Look, the roof is vaulted over there! Where does that door lead to?"

The little door in question had apparently been opened by force, to judge from the broken lock and the marks of some sharp instrument on the jambs. At present it was closed, but not fastened. What lay beyond? With a feeling that they had arrived at the crowning-point of their adventure, Deirdre opened it and peeped in. She found herself looking down from an eminence of about four feet into a bedroom. The room was in complete darkness, for the window was barred with heavy wooden shutters, but by the aid of her candle she could see it was unoccupied. Giving the light to Dulcie to hold, she cautiously descended, then aided her chum to follow. The door through which they had stepped formed part of the panelling over the mantelpiece, and when closed with its original spring would no doubt have been indistinguishable from the rest of the woodwork. The room, though neglected and in great disorder, nevertheless bore traces of recent habitation. The bed, with its tumbled blankets, had certainly been slept in. On the dressing-table, spread out on a newspaper, were the remains of a meal. A small oil cooking-stove held a kettle, and one or two little packets, probably containing tea and sugar, lay about. On the floor, torn into small pieces, were the shreds of a letter written in German. Dusty and untended as it was now, the room must once have been pretty, and bore strong evidence of the ownership of a little girl. On the walls hung framed colour prints of Millais's "Cherry Ripe", "Little Mrs. Gamp", "Little Red Riding Hood", and "Miss Muffet". In the corner stood a doll's house, a doll's cradle, and a miniature chest of drawers. A chiffonier seemed to be a repository for numerous treasures—a set of tiny alabaster cups and saucers, a glass globe which when shaken reproduced a snowstorm inside, a writing-desk, a walnut work-box, a small Japanese cabinet, and a whole row of juvenile books. Deirdre took up some of the latter, blew the dust off and examined them. They were volumes of Little Folks and Chatterbox of many years ago. On the title-page of each was written: "To darling Lillie from Father and Mother".

In greatest amazement the girls wandered round the room, looking first at one thing, then at another. How old the dust was that mostly covered them! Here and there it had been hastily swept away, to make a clearance for cup and saucer or provisions, but in general the little possessions were untouched. Even some New Year cards stood on the chest of drawers, bearing greetings and good wishes for the coming season.

"I want to see better," said Deirdre. "This wretched candle only gives half a light. I've never been in such a fascinating place. Help me, Dulcie, and we'll try and unfasten the shutters."

The heavy iron bar was old and rusty. It must have been in its place for many a long year. For some time the girls pushed and tugged in vain, then with a mighty effort they dislodged it from its socket, and let it clatter down. Deirdre slowly swung aside the shutter. After the faint light of their one candle, the flood of sunshine which burst in completely dazzled them. As soon as they could see, they peeped out through the dingy panes of glass. To their immense surprise they found they were looking into the Dower House garden. Then Deirdre suddenly realized the truth.

"Dulcie! Dulcie!" she cried, "I verily believe we're in the barred room!"

There seemed little doubt about the matter, when they came to consider it. The position of the window corresponded exactly with the closed-up one which had always faced them from the tennis-courts, and whose secret they had so often discussed. The mystery, instead of becoming clearer, seemed only to deepen. Why was one of the bedrooms in the Dower House filled with a child's possessions and sealed with iron bars, yet accessible from a cave on the beach, and evidently in present occupation?

The daylight revealed its extraordinary condition with great clearness; the dust, dirt, and cobwebs looked forlorn in the extreme. On a hook on the door, which presumably led into the Dower House landing, hung a net filled with hard wooden balls, and as the draught blew in from the opening over the fireplace, these swayed about and knocked with a gentle rapping against the panel.

"There's your ghost, Dulcie," said Deirdre. "That was the tap-tapping you heard in the passage. It wasn't a spook after all, you see."

"You were just as scared as I was," protested Dulcie. "I think I'm rather scared now. Let's go! Suppose whoever's been here making tea were to come back? I believe I'd have hysterics."

There was something in Dulcie's suggestion. It had not before occurred to Deirdre that it would be unpleasant if the owner of the kettle were to return and demand an explanation of their presence.

"We must put the shutters back," she decreed.

This was easier said than done, but after considerable trouble they managed to restore the room once more to its former state of darkness. Their candle was burning rather low, but they hoped it would be sufficient to light them to the mouth of the cave. With the aid of a chair they climbed on to the mantelpiece, passed through the door in the panelling to the vaulted chamber, and on into the subterranean passage. They scurried along as fast as they could without stumbling, partly from fear that the candle would go out, and partly in dread lest somebody should be coming from the entrance, and meet them on the way. It was with a feeling of intense relief that, bearing the last guttering scrap of candle, they at length emerged into the daylight.

"Here we are, safe and sound, and met no bogy, thank goodness!" rejoiced Dulcie.

"There's our bogy, waiting!" said Deirdre, pointing to a school hat which suddenly made its appearance from below.

"Gerda, by all that's wonderful!" gasped Dulcie.

Yes, it was Gerda who had followed them, and who now watched them as they came out of the cave. She was paler than usual, and there was a queer set look about her mouth.

"So that was what you wanted the candle for. You might have told me," she remarked.

The two girls began an animated account of their strange adventure. They were so full of it that at the moment it would have been impossible to avoid talking about it. Gerda listened calmly, though she asked one or two questions. She spoke with the constrained manner of one who is putting a strong control on herself.

"So you found nothing to explain the mystery?" she queried.

"Nothing at all. Is it Lillie who's living there and doing her own cooking?"

"And is she a girl or a spook?" added Dulcie.

"Spooks don't drink tea. She must be alive," said Deirdre. "I wonder if Miss Birks knows about her?"

"I guess we'd better not divulge the secret!" chuckled Dulcie. "What would Miss Birks say to us for trespassing in the kitchen-garden?—particularly when she's away."

"We should get into a jolly row!" agreed Deirdre.

"We shall all three get into one as it is if we don't go back quickly," observed Gerda.

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!"