Joey couldn't go to sleep that night. She was excited, and all kinds of thoughts went whirling round and round in her head, making sleep impossible.

The whole day had been exciting—the play had only been the culmination of it all. The walk to the station—the conversation about Professor Trouville and his queerness; on top of that the thrill of being coupled with Noreen in Gabrielle's invitation to the great match; the long talk about home-things with Miss Craigie in her bedroom; and then the play.

It was this last, probably, that turned her thoughts so much to Father, dying far away from them all, among his enemies.

The man who had been Father's special friend among the prisoners had come to see Mums, when the Armistice released those of our men who had survived the German treatment, and had told her that Father was taken from the prison camp in a dying state, and word had come back a few days later that he was dead.

Captain Verney had done his very best, delaying his own return, to find out for Mums just how he died and where he had been buried, but it seemed that no one knew or cared; and Uncle Staff had had no better luck when he went out with a War-Office permit to investigate a few weeks later. Mums and the children had just the one consolation of knowing that Father died for England just as surely as though he had been shot going over the top, to help them bear the thought of the long weeks of suffering and ill-usage which had come first. If only escaping from prison were as easy as it seemed in books and plays, Joey thought, tossing restlessly, she and Gavin would have been out in Germany with a file and a bottle of chloroform, and have set Father free before the Huns had time to kill him. But in real life you could do nothing except wait and wait and say your prayers, and take care of Mums.

Joey sat up in bed, and stared out at the dark window-pane so close to her. It was a mild, damp night—she threw off her quilt—perhaps she was too hot and that was the reason that she could not sleep. And while she was sitting up, she saw something flash in the darkness, and knew in a second what it was. A series of short blue flashes, coming from the dark.

"How funny!" was her first thought, and then she suddenly called to mind John's signalling instructions; that was the "call-up" in Morse. Somebody, it seemed, was going to practise his signalling now, at nearly twelve at night. Joey crept out of bed, and crouched on the window-sill so as to miss nothing.

There was disappointingly little to see; the people, whoever they were, were not nearly such keen signallers as John was. Something came from the side of the house—from her window Joey couldn't locate it exactly—three long flashes and two short ones. Then, a minute later, from the distance—one of the letters she had used with John—short, long, long, long, and then a short-long.

And that was all.

Joey sat crouched on the window-sill for quite a long time, but nothing more happened. Then, just as she was thinking of getting back to bed, someone came round the corner of the house far below. It was the Professor. She saw him unmistakably in the light of an electric torch, which he must have pressed for an instant, perhaps to show him the path. He slept, as Joey knew, in a room on the ground floor of the lodge; he had chosen it because he so often worked late at the Lab and did not want to disturb the lodge-keeper and his wife.

She wondered whether it was he who had been signalling; somehow you would not expect an ill-tempered chemistry professor to want to practise signalling, especially about twelve o'clock at night.

Of course, German spies used to signal in wartime, but then the Professor wasn't German: his name was French, and the look of him was more French than German, and he spoke with a French accent, and, most important proof of all, he had laughed and been quite genial about the play, instead of giving himself away as Hamlet's uncle had done. Besides, English people had settled they wouldn't have Huns creeping in among them again, and though Colonel Sturt had seemed to think they might be doing it, Cousin Greta had not agreed with him.

Joey set to work to see if she could remember the signalling; if the Professor were really keen on it, and went on being in the pleasant temper he had shown to-night, perhaps she might ask him some questions.

Dash, dash, dash, dot, dot. She went through the alphabet; there were no letters like that; then it must be a numeral. John had taught those as well. The long numerals were the ones he had insisted on, because he thought it made things so slow to have to signal f—i—before you sent a numeral.

Dot, dot, dot, dash, dash—Joey had it: it was three. And immediately after it—a pause between—dot, dash, dash, dash, dash—31. Thirty-one. That had been all. The other signal had been an answer, and that was a good deal more puzzling. For surely dot, dash, dash, dash, stood for J and dot-dash for A, and yet Ja had no sense. Joey supposed she must have forgotten the alphabet, and went to sleep at last, trying to remember.

The play influenced her dreams more strongly than the signalling. It acted itself again through her sleep, only it refused to act itself straightforwardly. Everything and everyone seemed to stick and repeat, including Noreen—so ready of tongue. Her German, which Joey, who had never learnt any, had so admired last night, had quite deserted her; the only word she seemed able to make use of was Ja. No "Tod und Teufels." No "Ach Himmels." She said, "Ja! ja!" and that was all, and then the dressing-bell sounded, and Clara the housemaid came in with a clatter of cans, and it was morning.

Joey was sleepy, and did not get up till the last possible minute; and then it meant a frantic scramble to get dressed in time, and no chance of talking to the others.

As it was, she was just a moment late, but grace had not yet been said, for the girls were still standing round the tables, so she hoped to escape the order mark which was her due. She slid noiselessly into her place, and then became aware that Miss Conyngham was speaking—Miss Conyngham, who never appeared at breakfast, but had it in a stately manner, befitting Head Mistresses, in her own room. She was standing at the top of the long centre table, where Ingrid and other great seniors sat, and there was a little line drawn between her eyebrows, as though she were worried. She was evidently in the middle of a sentence. Joey listened, trying to make out what it was all about.

"... And when Professor Trouville went to the Lab before breakfast this morning somebody had been there, breaking bottles, mixing specimens, and doing other acts of altogether stupid and unreasonable mischief. The door was as usual locked; the girl, whoever she was, had got in at the window by the steps, which Professor Trouville had for once left open. That being so, I quite exonerate the juniors; no girl under thirteen could scramble up to that window. Professor Trouville tells me that he has had trouble with several of the girls in Remove II. B; if any girl there has done this wrong and foolish thing, it is up to her to own it now—for the honour of a school which does not turn out cowards."

There was a thrilling pause, while Miss Conyngham's far-seeing eyes looked round expectantly, and the Professor stood just behind her, silent, watchful, impassive, with half-closed lids. Miss Conyngham seemed to have no doubt that somebody was going to speak—a little of the colour faded from her face and the light from her eyes, when there came only silence.

"I trust the girl who has done this thing to tell us now," she said.

And still there was silence.

Miss Conyngham's face grew a little stern. "If any girl here knows anything of the matter, though not herself responsible, I wish her to speak out."

Still silence. The Professor whispered something to Miss Conyngham; she shook her head, then spoke to the senior mistress present:

"Breakfast had better go on now, Miss Wrestow; I will deal with this matter later."

She went out, followed by the Professor.

"What on earth is the matter?" Joey whispered, squeezing hastily into a place by Noreen. "Something happened to the Lab—what luck for you stinks people! You won't be able to do any."

Noreen was rather cross. "Don't be such a young silly; don't you see this is going to be a horrid plague for us? That old beast has put the Head on to Remove II. B just because he doesn't like me, I believe, and of course we're suspected. You heard what Miss Conyngham said."

"But who's done what?"

"Somebody's got in and smashed some of his hateful old things there; I should think the cat as likely as not; but of course he fastens it on to us. Just like him. As if I'd go and do a silly kid's trick like that!"

"Of course you wouldn't. It's a shame," comforted Joey. "But of course the Head would never think so. S'pose she just had to ask. When does he think we did it?"

"Last night. He thought we were excited about the play and aiming it at him, and somebody went in and did it after we were supposed to be in bed."

"But he was there himself much later than that," almost shouted Joey. "I saw him out of my window."

"Well, he is the limit, then. Let's tell Gabby that."

The information was passed up to Gabrielle at the other end of the table; she came round to the other two the minute breakfast was over. "What's this, Joey?"

Joey began upon the story of last night, but hadn't got far in it before Ingrid Latimer bore down upon the group. "Joey Graham, where are you? You are to go to Miss Conyngham at once. She told me so before she went."

"Oh, bother! Just when you were telling us," Noreen broke out. "Cut along, and do hurry. I shall burst if I don't know the rest before First Lesson."

Joey ran, arriving at Miss Conyngham's door in a decidedly breathless condition.

Miss Conyngham was there with the Professor. He was speaking, but stopped as Joey came in. Joey had an idea that behind his pale, impassive face he was very angry.

"Jocelyn," said Miss Conyngham gravely, "I want to ask you one or two questions by yourself."

"Yes, Miss Conyngham," Joey answered wonderingly.

"Have you gone outside at night? Think before you speak."

That question did not need thinking about; Joey remembered that home-sick first night far too vividly to hesitate. "Yes, Miss Conyngham."

"When?"

"The first night I was here. I got out on the roof; didn't Matron tell you I spoilt my quilt? She jolly well takes care to go on telling me——"

"Answer only my questions, please. You got out on the roof that first night. For what reason?"

Joey could not say that Noreen, Syb, and Barbara had been horrid to her; she turned red and hesitated. The Professor glanced quickly at Miss Conyngham.

"For what reason, Jocelyn?"

"Oh, just I wanted to. Of course, I didn't know it was going to rain on my quilt."

"Never mind the quilt. How often have you done it since?"

"Never, Miss Conyngham."

The Professor's black eyebrows lifted just a shade. Joey saw them and felt angry. Didn't he believe her?

"You are quite sure of that, Jocelyn?"

"Yes—honour."

"Last night," Miss Conyngham said slowly, her eyes on Joey's face, "the Professor saw a girl, a tall, slim girl in a short frock, climb in at the window of the Laboratory sometime after you were all supposed to be in bed, but before the servants had locked up. He was not near enough to be quite sure about her—but this morning he found this handkerchief under the window."

She held out the handkerchief—a small blue-bordered one, rather grubby. Joey's name, in Mums' marking-ink, stared up at her from one corner. It was certainly hers—it was, in fact, the handkerchief she had used last night; she remembered drying her hands with it after helping Barbara to carry the cauldron of boiling water across the stage. She had thrust it back into her sleeve, she remembered, when Noreen demanded she should tell the audience how many syllables the charade had.

"Yes; it's mine all right—but I don't know how it got there," she said, staring at it.

"Is there anything that you would like to say to me quite alone?" Miss Conyngham asked her.

"You don't think I went to the Lab when I've said I didn't? I don't tell lies," Joey flared.

"No, I believe your word of honour, Jocelyn," Miss Conyngham said, and she looked very straight at the Professor.

Joey heaved a sigh of relief. "Well, that's all right. Thanks awfully. Do you want me any more, Miss Conyngham, or can I go now? For Noreen and Gabby are frightfully keen to hear about the things I saw last night."

She turned to the Professor. "I say, were you walking round the place all the time between ten and twelve? You must have got wet! If it had been one of us, we'd have caught it from Matron for staying out in the rain."

"What do you talk of? I picked up the handkerchief, suspecting not-ting, and returned to the Lodge," the Professor said annihilatingly. "It was not till I visit the Laboratory to make a leetle experiment this morning, that I find my eyes haf not deceive me—and then I looked at the name on the handkerchief, and learn who do me this injury."

"I've told Miss Conyngham I didn't go into the Lab," Joey declared, growing angry in her turn. "I haven't been near the place since you were so frightfully cross with me for tidying the day I came. And you needn't be surprised that I thought you were walking about all that time, for you were there at twelve, when you were signalling. I saw you. I dare say you came back to do it—only, it was a natural thing for me to think, wasn't it?—not rudeness, like doubting a person's word. I'm sorry if I've been rude, though; and I think you signal splendidly—so jolly fast. I couldn't keep up with you."

The Professor made a contemptuous gesture with his hands, stained and blunted at the fingertips.

"She dreams, this child. I haf no knowledge of the signalling. But for the other matter, Madame, may I ask that you will question further?"

"No, Professor, I shall not do that," Miss Conyngham said firmly. "Jocelyn has given me her word of honour that she had no hand in the matter, and I trust my girls. Someone else must have taken her handkerchief by accident. I need hardly tell you that I shall look most carefully into the business and discover the culprit; but I cannot act as you suggest, or disbelieve the word of a child who has always shown herself truthful. Jocelyn, you may go; I am satisfied with what you have told me; but until the mystery is cleared up there will be no leave out for any Redlands girl, and you may tell the girls so."

"Not for the match?" cried Joey, in dismay.

"Not for the match; except, of course, for the players," Miss Conyngham said quite decidedly. "Someone is behaving like a dishonourable coward, and until she owns up the whole school must be punished. That will do, Jocelyn."

The Professor made a quick step towards Miss Conyngham. His expression made Joey think of the day he had found her trying to perform the duties of a "scholarship kid."

"If the word of the young lady is to be taken before mine, Miss Conyngham, I must ask you of your goodness to seek another Professor of Chemistry," he said. "And it would be much to my convenience if you could find him by the end of dis vairy month, since your young ladies here haf no desire to learn of me—and I therefore receive insults on all sides...."

"Run away, Jocelyn," Miss Conyngham ordered, and Joey obeyed of course, though it was a tantalising moment to be ordered out. Would Miss Conyngham and the Professor make friends again, she wondered, or would she accept his resignation and let him leave them as he asked to do by the end of the month?

The end of the month—why, that would be the 31st, of course. Joey thought of Noreen's words, "We're living in a mystery." Noreen had been joking, but it began to look as though her joking words were coming true.

It was then it occurred to her that the minute the ban on going out was removed, the person to consult was John. But meantime the school was under arrest and the culprit had still to be found. Joey made her way back to the others, and announced Miss Conyngham's depressing ultimatum on the way to Remove II. B classroom. By Break the whole school knew it, and the Head of the Upper School and the Head of the Lower met for a council of war.