Joey had shouted till she was hoarse; she had flung her inconsiderable weight upon the door again and again in the hope of forcing it—a feat performed with misleading ease in all Gavin's books of adventure.

She had to stop at last from sheer exhaustion, and then it was, when there was nothing else to do, that she began to think.

The Professor had locked her in, though she had called to him. So he had known that she was there. He was not deaf, so he had locked her in on purpose. That was the first thought which came at all clearly to her mind. The second was more puzzling still—why had he done it? Joey never knew exactly at what moment it was that a suspicion about the Professor crossed her mind. Her mind had travelled quite a long way first—as far as Mote. What would Cousin Greta say when the car came back without her? Oh, but it wouldn't—somebody would look for her. Yes, they would look, but would they look in the right place, for no one knew where she had gone—no one but little Tiddles? All the girls would have gone by the time Cousin Greta's car came for her. Syb and Barbara most likely, and Gabrielle and Noreen most certainly, would never have given up hunting for her if she were missing in a mysterious way; but then they were her friends. The maids were very kind and good-natured—they would look for her in the Blue Dorm and the playroom, and one or two more likely places of that kind, but it was not to be expected they would go on looking after that.

They would probably think she had changed her mind, and gone off in one of the brakes, and tell Cousin Greta's chauffeur so. He would go back to Mote without her, and Cousin Greta would think her a girl who had been even ruder than on the former occasion, with less excuse; and John would think her a slacker, which was worse. Joey felt despairingly miserable at the thought of John's contempt; and with that misery came naturally the thought why John had wanted her to come to-day. She was not very clear as to the reason herself; but it was certainly something to do with the Professor's signalling. And somewhere at that point a suspicion lifted its head.

Joey groped for a box in the darkness, and sat down to consider. All kinds of queer things about the Professor kept shifting in a muddled kaleidoscopic whirl across her memory—his curious anger on the first day they had met, the afternoon when she had tried to perform the duties of a scholarship kid by tidying the Lab; the violet handkerchief he used, with the queer marks on it; his prowls and signalling at night.

Sitting there in the darkness, with her fingers pressed tightly on her eyeballs to help her to think, Joey saw again that handkerchief hung out to dry upon the nursery guard of the First Form Room, and the little yellow marks that came out with the heat, and disappeared when the handkerchief was cool again. They might just have been washing marks—if washing marks ever did a thing like that.

Joey pressed so hard upon her eyeballs that she saw violet stars instead of handkerchiefs, and then, in the midst, she saw again distinctly those funny little marks which had shown themselves between the red-worked initials of the Professor's name, —.—...—

Dash, dot, dash, and dot, dot, dot, dash—that was Morse, and it spelt two letters, K and V. What could they stand for? The Professor's name was Achille, so he had informed Noreen, when, greatly daring, she had inquired one day a week or so back, after a particularly peaceful "stinks" class, when she had not been addressed as Fathead. Besides, what person in their senses would have a name first worked, and then fixed on in some kind of invisible ink, and in Morse?

K V! K stood for Kenneth or Kitten or Kultur, or Kamerad, or Kaiser. (It was odd how many German words came unbidden to her mind.) And V might be Vauxhall or Vaterland! Yes, Vaterland was spelt with a V, though it sounded as if it were an F. Joey found that the two words Kaiser and Vaterland fixed themselves in her mind, and joined together with John's odd tone about the signalling, and the Professor's midnight expedition, and that lettering that she had read—the figures—31, and then the answer Ja. The 31st was to-day, and Ja, as Noreen had used it in the wonderful charade, meant Yes. What was going to happen to-day, and who had answered the Professor's signal?

Joey's mind went back slowly over the ground of this exciting month at Redlands, till it reached that Sunday spent at Mote, when she had come back to school alone, and been caught by the sea-roke, and had taken shelter in the Round Tower. The jumpy young man had certainly been doing odd things down below, and he had not been at all pleased to see her there at first; that was certain, though he had been quite kind and nice afterwards, and told such interesting stories. It had never occurred to Joey that the stories might have been intended to have a deterrent effect upon her.

But could the young man's obvious jumpiness have anything to do with the mysterious business? Noreen had thought so, but Joey hoped it hadn't, for if it were he who had answered Ja it meant he was a German, and she didn't want him to be that. It was much easier to think of the Professor as a German; Joey had rather liked the young man, in spite of a slight natural contempt for his nervousness. And then, quite suddenly it all came over her; a sense of some great danger, which was none the less frightful, but rather the more, because it was all so vague.

Colonel Sturt had thought that Germans were creeping back into the country—Germans in no way altered by the wars, inside. And they were clever, everyone knew that—quite clever enough to call themselves French, and talk with a French accent that was good enough to take people in. Suppose she were right in what she guessed, and the Professor was not French at all but German, what was he doing in the school Lab? And what had he taken away with him from the Lab this 31st October, when the only person who could see what he was doing was locked into the closet, and likely to remain there till the girls came home from the match, and a proper search was instituted? Joey remembered that curious little box which through the keyhole she had seen the Professor fit so carefully into his cigar case. It was not only something precious to him, but it was something he did not wish anybody else to see. And if he were a German, it was something that no one must see, because it was something that would do harm—not just to an insignificant person like herself, but to England. When Joey thought that she had to hold herself in, hard; or she would have flung herself upon the door, and beaten upon it in a frenzy till she was worn out. For everybody who might look for her was away, and no one knew anything except her imprisoned self; and the Professor was probably away by now with the mysterious box, putting every minute more distance between himself and Redlands.

But she forced herself to keep cool. She would want all her powers if she was to do any good.

She had heard the great clock from the old clock tower strike one quite a long time ago; yes, the School would have started. And there was not the tiniest bit of a window in her prison; it was all dark and close and filled with bottles that rattled and fell over if she moved, and boxes with sharp corners that cut her shins.

Mingled with the other stuffy smells there was the rank smell of newly fallen plaster. Though it was dry enough now there had been a good deal of rain last week, and Noreen had mentioned casually that the Professor had been very cross because some rain came through the closet roof and spoilt one of his "preparations."

Joey stood up cautiously, and, crouching on the floor, felt for the fallen plaster, groping before her with both hands. Of course she banged her head against a shelf, and upset a bottle, which smelt overpoweringly, but she found the plaster, and stood up again considering. Somewhere there must be a tile off; and if one had gone, she could surely pull away more, and attract attention from above.

Only how did one get up there? Shelves, of course! Joey cleared a space on the lowest shelf, as well as she could in the darkness, and scrambled on to it, clinging to the one above. There was a crash and the tinkle of broken glass, but she was reckless now. It didn't matter if she smashed all the bottles in the "Stinks Shop," as long as she got out before it was too late.

Hanging on with one hand, she pushed away some bottle from the next shelf, and pulled herself up on to it; and so, with much bruised shins, she landed at the top and stood upright, the roof in her reach at last.

She had expected to find a hole through which she could put her hand, but she actually only felt a cold whistle of wind, and had to pick at the lath and plaster for a good five minutes in the darkness before she could see any light through, and then only a chink.

She pushed with all her might, but nothing happened. There was a great shrieking and whistling above her head, and she realised that the wind must be rising; but nothing happened for all her efforts. She had thought that when one tile was off the others would follow naturally, but it seemed that only happened when you didn't want it to do so.

She must have something to push with—a shoe would do, only she must remember to put it on again before she stepped down upon the broken glass strewing the floor.

Joey unlaced one of her strong shoes, not without upsetting another bottle in the process, and, standing on tiptoe on the top shelf, began a violent assault upon the breach in the roof. If she could only make a hole large enough to get her head through, she thought, she would shout and shout and shout till somebody heard and came to let her out.

It is very tiring to stand on tiptoe, especially when one foot has no shoe on, and bang at something above you. Joey's arms ached and her toes ached, and her back; the height at which Calgarloch had stood amazed was hardly enough for her purpose; she had to stretch to her utmost capacity. "Lucky it wasn't Gabrielle who got shut up," she thought to herself, and then, through all her anxiety and struggling, came the thought of her two friends, Noreen and Gabrielle, and the plans they had made together for the afternoon. What were they doing now? Joey wondered. Were they remembering to look out for her? Yes, she felt sure they would do that; they were the kind of friends who stood by you. If only she had them to stand by her now!

Her attack on the roof did not appear to have any effect but that of bringing down unwanted showers of plaster that made her choke and sneeze and, more than once, gave her a nasty knock. But she kept on doggedly at her task—she had to do it somehow. English people couldn't wait to ask whether the job was do-able when your country wanted it done. And all the time she was imprisoned here the Professor was free to do what harm he liked, because nobody knew about him but herself.

Joey redoubled her efforts, and a tile went at last. She could hear it fall on to the ground below. One gone—perhaps the next would be easier. She dropped her tired arms for a moment to rest them, and in that moment the big clock struck two. Only half an hour to the time the match would start—that gave her a fresh sense of urgent need of haste. She smashed furiously at the roof, and her shoe went through it and stuck so fast that she nearly came off the narrow shelf in her effort to dislodge it. In spite of her anxiety and her aching arms, she had to giggle at the thought of how absurd a shoe must look from below, sticking up through a hole in the roof.

It came away at last, and something happened at the same moment: there were steps outside and the key turned in the lock—somebody was coming in.

Joey shouted at the full pitch of her lungs, as she tumbled down recklessly from the shelf and hopped across the broken glass to the door.

"Oh, let me out! I'm shut in."

There was an exclamation, and the voice of Frances, the superior parlour-maid who had opened the door to Joey on her arrival, called, "There, Miss Tiddles! You were right—she was here."

A key slipped about in the lock of the closet door. "Miss Jocelyn, what have you done with the key?" Frances demanded.

Hope died in Joey's heart. "The Professor took it."

"I think he's just gone," Frances said. "I'll try this key again; the locks are nearly the same."

"Oh, Frances, do try, like a brick!" poor Joey cried in a frenzy. The Professor only just gone; there might be time to stop him yet. Fennell the gardener was a large man, and he was probably somewhere about the place.

The key rattled, half-turned, stopped. "Bother!" cried Frances. "Run, Miss Tiddles, there's a dear, and see if the Professor's gone yet."

Wonder of wonders. Tiddles must be in or near the Lab—Tiddles who had such a horror of it. But Joey had not time for astonishment. "Stop her! Don't let her go!" she cried. If the Professor knew that she was escaping from her prison!

Frances seemed to be bending all her powers to the turning of the key. She was a determined person, accustomed to resisting the onslaughts of the Lower School upon the sugar basin, when she poured out the tea. "Almost got it—there!" she said, with a gasp.

The key wheezed and turned; the door opened—Joey was free. "Thank you, Frances!" she gasped, and fled past Frances, past little Tiddles standing solemn-eyed and scared at the top of the Lab steps, and away towards the house. She had put on her other shoe while Frances was wrestling with the key; but it was a dirty, hatless girl, with torn stockings and scratched hands, who flung herself round the angle of the house, as the steadily decreasing throb, throb of a motor-bicycle announced that the Professor was making full speed down the drive, and out to the world beyond.

Joey did not call the gardener. The Professor had gone; he would be no good now. She dashed through the side door, and fled like the wind to Miss Conyngham's room. It would be empty now, of course; there never was such an emptiness anywhere as there was about the College to-day. But the telephone was there, and the telephone was what she wanted just now. John was the one person she could think of as able and willing to help; one wouldn't go to Frances with an unsupported story like hers. Frances would look at you as though she was thinking "Not another lump—one is plenty, Miss Jocelyn," and there would be an end of it. But John would understand.

She put the call through with feverish haste, and a hand that shook a little. Her knees were trembling too, and her mouth was dry, but it did not strike her that she had had no dinner. Other things were mattering so much.

A maid's voice answered her. "Can I speak to Mr. John Sturt?" Joey asked, trying to sound ordinary and business-like. "Oh—would you give him a message and say it's dreadfully important, please? Say I'm coming, and I don't think the Professor is French after all—he'll know—and he's just gone off in a tearing hurry, and he took things from the Lab in his cigar case, and he's on a motorbike, and he locked me in." Joey jammed on the receiver, and, without waiting to get coat or hat, fled out of the front door and down the drive. She hoped Miss Conyngham wouldn't be very vexed by what she was going to do; but anyhow she would have to do it. She set out running through the iron gates and along that straight marsh road, along which the Professor must have gone first. She had forgotten to ask that a car should be sent to fetch her, but somehow she had no doubt that would be done. Only, she could not wait.

Her faith in John was justified. John must have beaten all speed limits. She hadn't run a mile, battling with the fierce side-wind that seemed to take all her breath away, when a cloud of dust in front of her, resolved itself into a long-nosed grey racing-car; there was a rending screech, and John's voice hailed her.

"Good! Thought I'd meet you; jump in. Mind my crutches."

Joey scrambled up, and he backed and turned the car neatly. "Did you meet him?" she demanded breathlessly.

"Who? The Professor? No."

"Didn't you? I thought he'd go to the station or something," Joey said blankly. "John, I believe he's a German in disguise."

"Bright Kid," John agreed. "I 'phoned to the Police Station before coming to meet you, but we could do with some more information. What's this about his locking you in?"

Joey told breathless reams, without a single comma.

John whistled. "H'm! Now, where's the beggar gone?—that's the question."

The car had reached the point where the roads branched, to the right to Mote Deep Station and so on to the Grange; to the left towards the sea and Deeping Royal.

"If he only left just before you 'phoned I ought to have met him," mused John. "There isn't a train for three-quarters of an hour—and you bet a Hun knew that—they're so thorough. He must have gone to the Junction, and then he would pass Mote, of course."

"Think he went to have a squint at the hockey match?" suggested Joey doubtfully. John shook his head at her, more in sorrow than in anger.

"Joey! Joey! Think I left my distracted relations in the middle of lunch, and brought my own special and particular car, just sent me by the Governor—you shall see all her points later on when we've settled this little affair—to hear you making cracked suggestions like that. If our gentleman is out for mischief, he won't be specially keen to locate himself in the midst of a large crowd of astute Redlanders, you bet. Stand up in the seat—hold on to my shoulder, that's sound enough, and see if you can locate him anywhere."

Joey obeyed. She was breathless with excitement, and though John had jeered at her suggestion about Deeping Royal, he had certainly seemed impressed by her story, particularly by the violet handkerchief and the box packed in the fat cigar case. Of course, one would expect a big boy of seventeen, in naval uniform, to laugh at a girl of only thirteen; he wouldn't be human if he didn't.

She got upon the driving seat, holding to John's shoulder with one hand and trying to clear her hair out of her eyes with the other. The wind was furious; she found it quite hard to keep her footing, though John's car was low—a typical racer, if she had known more about cars. John's father had known his son's taste to a nicety; John wasn't out for ornament.

She saw the twisted chimneys of Mote Grange far away, and the corrugated iron roof of the station in the foreground. Then she looked along the road to the left.

Clear in the intensely clear atmosphere that often goes with furious wind, she saw the twin towers of St. Philip and St. James standing against the grey line of the sea. But not one thought did she give to the great match that would be starting there in a very few minutes from now; for not so very far away, upon the white raised road, a figure was on foot beside a motor-bicycle, pushing it, running with it—on foot!

She grabbed John's shoulder. "Oh, John, I'm sure it's him—the Professor—and his bicycle won't go, or something."

"By Jove!" John cried. He glanced up at Joey with a grin. "I suppose I ought to scoot to Mote and get help, and drop you in Aunt Greta's charge."

"John! he'd get away!" shrieked Joey.

John grinned again. "He probably would. We won't do what we ought. Get down, Kid. I'm going to let her rip."

Speed record certainly did not concern John just then—the long-snouted racer leapt forward, bumping wildly with the pace which John got out of her.

Joey crouched low in the car, feeling as though her hair was being torn from her head, but blissfully happy all the same. She had absolute confidence in John; he would deal with the Professor. It did not occur to her that seventeen-year-old John on crutches might not be a match for a determined man in perfect health. Her only fear was that the motor-bicycle might get going too soon.

There are few bends in a fen road. Those who made them may have had the roads of Russia in their minds, for fen roads tend to be drawn with a ruler from end to end.

They saw the Professor, still struggling with his bicycle, more than a mile away. They saw him run pushing his machine, and this time it fired and went.

Joey said, "Oh!" in deep disappointment. John grinned again.

"Some race, Joey! Hold tight—if he can rip, so can we."

He only spoke once again. "You might loosen my dirk, Kid; it's your side."

Then he bent himself to the wheel, and got every inch of speed out of the car that was in her. The distance between car and bicycle diminished slowly.

The wind roared and tasted salt to the lips; the towers of St. Philip and St. James stood higher and higher. And now the high parapet of the reservoir was in sight. When they passed that, Deeping Royal was not three-quarters of a mile away.

"He must be going to see the match after all!" shrieked Joey. She had to scream to run any chance of being heard above the roar of wind and the racing, lurching car.

There was still half a mile between car and bicycle when the bicycle was up to the reservoir, and the Professor clapped on his brakes, and dashed for it on foot.

"John!" Joey screamed. The play, which the occupants of Blue Dorm had acted to celebrate Miss Craigie's return, rushed suddenly into her mind. She remembered the box of tiny bottles hidden in the cigar case, and the thin cruel smile she had seen on the Professor's face as she looked at him through the keyhole.

Perhaps John had the same thought in his mind. The car bumped furiously, and all but overturned.

The Professor disappeared round the angle of the reservoir.