He could not help gripping his revolver as the stairs creaked again under Dr. Baumgartner; he had gripped it more than once already with the hand that was not holding Phillida's. The doctor was coming down in a hurry, as though he had indeed forgotten something. But he pa.s.sed the open drawing-room door; they saw him pa.s.s, jingling a bunch of keys, and never so much as glancing in on the way. It was the dark-room door he opened.

Now he would find out everything! They heard a match struck, and saw the faint light turn into a strong deep crimson glow. The door shut. The children stood listening in the dark.

Running water, and the c.h.i.n.k of gla.s.s; the tapping of a stoppered bottle; the opening of the dark slide; these stages the younger photographer followed as though he were again looking on. Then there was a long period without a sound.

"He's developing now!" whispered Pocket, close to the folding-doors. He caught the sound of laboured breathing on the other side. "There it is-there it is-there it is!" cried the doctor's voice in mingled ecstasy and mad excitement. A deep sigh announced the blackening of the plate at the conclusion of the first process. A tap ran for a moment; interminable minutes ensued. "It's gone! It's gone again!" cried the wild voice, with a sob; "it's gone, gone, gone like all the rest!"

One listener waited for the pa.s.sionate smashing of the negative as before; but that did not happen again; and then he wondered if it was being put straight into the rack with the others, if the damage to the locker had been discovered at last. He never knew. The door opened. The red glow showed for a moment in the pa.s.sage, then went out. The door shut behind Baumgartner, and again he pa.s.sed the drawing-room, a bent figure, without looking in. And the flagging step on the stairs bore no resemblance to the one which had come hurrying down not many minutes before.

"I must go to him!" said Phillida in broken undertones, and her grief communicated itself to the other young sympathetic soul, for all the base fears he had to fight alone. Personal safety, little as she might think of it, was the essence of her position as opposed to his; and he was of the type that thinks of everything. She left him listening breathless in the dark. And in the dark she found him when at length she returned to report the doctor busy writing at his desk; but a pin's head of blue gas glimmered where there had been none before, and a paper which had been trodden underfoot now rustled in Pocket's hand.

"Does he know I'm here?" he asked.

"I don't think so. We never mentioned you. I believe he's forgotten your existence altogether; he began by looking at me as though he'd forgotten mine. He says he wants nothing, except time to write. He seems so strange-so old!"

Again the break in her voice, and again the boyish sympathy in his. "I wonder if something would be any comfort to you?"

"I don't think so. What is it?"

"Something I saw in the paper he brought in with him. I lit the gas while you were upstairs."

Phillida turned it out again without comment.

"Nothing that you saw can make any difference to me," she sighed.

"Do you remember my saying there must be another man in these-mysteries?"

"I think I do. What difference does it make? Besides, the man you meant is in prison."

"He isn't!"

"You said he was?"

"He was let out early this morning! Let me light the gas while you read it for yourself."

But Phillida had no desire to read it for herself. "I doubt if there's anything in that," she said; "but what if there were? Does it make it any better if a man has an accomplice in his crimes? If he's guilty at all, it makes it all the worse."

THE FOURTH CASE

The boy and girl sat long and late in the open window at the back of the house. The room would have been in darkness but for a flood of moonlight pouring over them. The only light in the house was in the room above, and they only saw its glimmer on the garden when a casual cloud hid the moon; but once Pocket had crept out into the garden to steal a look at the lighted window itself; and what he saw was the shadow of a huge bent head smoking a huge bent pipe, and dense clouds of shadow floating up the wall and over the ceiling.

It seemed hours since they had heard footstep or other sound upstairs or anywhere. There had been a brisk interval-and then an end-of more or less distant hansom-bells and motor-horns. There was no longer even a certain minute intermittent trembling of trifles on the walnut-tables, to which Pocket had become subconsciously accustomed in that house, so that he noticed its absence more than the thing itself. It was as though the whole town was at rest, and the tunnels under the town, and every single soul above or below ground, but those two white faces in the moonlight, and perhaps one other overhead.

Pocket wondered; it was so long since a single sound had come down to their ears. He wanted to steal out and look up again. Phillida was against it; perhaps she was wondering too. Pocket, as usual, saw what he did see so very vividly, in his mind's eye, that he shivered and was asked if he felt cold. The whispered debate that followed was the longest conversation they had that night. The window was not shut as a result of it, but Pocket fetched his overcoat on tiptoe, and it just went over both their shoulders, when the chairs were drawn as near together as they would go.

The ragged little garden was br.i.m.m.i.n.g over with moonlight from wall to wall. The unkempt gra.s.s looked pale and ghostly, like the skin of some monstrous wolf. The moon rolled high in the sky and clouds flew above and below the moon, varying in pace as well. Yet it was a still night, and Pocket did not think that he had broken the stillness, until the door burst open behind them, and Baumgartner stood there, holding his lamp aloft. The wick was turned too high, the flame ran up the chimney in the draught, and for an instant a demoniac face flared up behind it. Then the chimney cracked, and fell in a tinkling shower, and the doctor was seen whirling a naked tongue of fire about his head. The boy drew back as the lamp flew through the open window, within an inch of his nose, and crashed upon the path outside.

The trio stood without a word in the moonbeams; but the doctor was breathing hard through his teeth, like a man wrestling with himself; and at last he laughed sardonically as though he had won.

"A lamp like that's a dangerous thing," said he, with a kind of forced solemnity and a shake of the head; "you never know what may happen when a lamp does that! I'm glad the window was open; it didn't go very near my young fellow, I hope?"

And he took Pocket playfully by the ear, but pinched it so hard that the boy could have screamed with pain.

"It would have served you right," continued the doctor, before Pocket could find his tongue, "for sitting up so late, and keeping a young lady from her bed to bear you company. Come, Phillida! I shall have another word with you, young fellow."

The two words to the girl were in a different key from all the rest. They were tolerant, conciliatory, tenderly persuasive. The rest was suavely sinister; it made her hesitate; but Pocket had the presence of mind to bid her a cheery good-night, and she went, closely followed by Baumgartner.

Posted once more at the open door, the boy heard Baumgartner on the next flight, soothing and affectionate still, allaying her fears; and his own surged into his throat. He looked wildly about him, and an idea came. He opened the front door wide, and then stole back through the conservatory into the moonlight. He heard Baumgartner coming down before he gained the garden. He tore to the end of it, and cowered in the shadow of the far wall.

The doctor came running into the moonlit room, but not for a minute; it looked as though he had run out first into the road. In the room he lit the gas, and Pocket saw him have a look in all the corners, but hardly the look of a seeker who expects to find. Some long moments he stood out horribly at the open window, gazing straight at the spot where the fugitive crouched a few inches out of the moonlight and hugged the revolver in his pocket. He seemed to see nothing to bring him out that way, for he closed that window and put out the gas. The trembling watcher heard the front door shut soon after, and saw another light in Baumgartner's room the minute after that, and the blind drawn down. But on the blind there lagged a cloud-capped shadow till the doctor's pipe was well in blast.

There were no more shadows after that. The moon moved round to the right, and set behind the next house. The sky grew pale, and the lighted blind paler still, until Baumgartner drew it up before putting out his light.

Pocket was now too stiff to stir; but it was not necessary; the doctor had scarcely looked out. There was a twitter of sparrows all down the road, garden answering to garden. The sun came up behind Pocket's wall, behind the taller houses further back. And Baumgartner reappeared at his window for one instant in his cap.

The front door shut again.

Down the garden ran Pocket without the least precaution now. There was a gravel pa.s.sage between the tradesmen's entrance, on the detached side of the house, and the garden wall. This pa.s.sage was closed by a gate, and the gate was locked, but Pocket threw himself over it almost in his stride and darted over into the open road.

Just then it was a perfectly empty road, but for a gaunt black figure stalking away in the distance. An overwhelming curiosity urged the boy to follow, but an equal dread of detection kept him cowering in gateways, until Baumgartner took the turning past the shops without a backward glance. Pocket promptly raced to that corner, and got another glimpse of his leader before he vanished round the next. So the spasmodic chase continued over a zigzag course; but at every turn the distance between them was a little less. Neither looked round, and once the boy's feet were actually on the man's shadow; for half the streets were raked with level sunlight, but the other half were ladders of dusk with rungs of light at the gaps between the houses. All were dustier, dirtier, and emptier than is ever the case by night or day, because this was neither one nor the other, though the sun was up to make the most of dust, dirt, and emptiness. It was before even the cleansing hour of the scavenger and the water-cart. A dead cat was sprawling horribly in one deserted reach of wood-paving. And a motor-car at full speed in a thoroughfare calling itself King's Road, which Pocket was about to cross, had at all events the excuse of a visible mile of asphalt to itself.

Pocket drew back to let it pa.s.s, without looking twice at the car itself, which indeed was disguised out of knowledge in the promiscuous mire of many countries; but the red eyes behind the driver's goggles were not so slow. Down went his feet on clutch and brake without a second's interval; round spun the car in a skid that tore studs from the tyres, and fetched her up against the kerb with a shivered wheel. Pocket started forward with a cry; but at that moment a ponderous step fell close behind him; his arm was seized, and he was dragged in custody across the road.

"Your boy, I think!" cried one whom he had never seen before, and did not now, being locked already in the motorist's arms.

"When did you find him?" the father asked when he was man enough, still patting Pocket's shoulders as if he were a dog.

"Only last night when I wired."

"And where?"

"In the house where you and I couldn't make ourselves heard."

The schoolboy flared up through all his emotion.

"Why, I never saw you before this minute!"

"Well, I've had my eye on you, more or less, for a day or two."

"Then why didn't you wire before?" demanded Mr. Upton, quite ready to mask his own emotion with a little heat. "I didn't get it till after nine o'clock-too late for the evening train-but I wasn't going to waste three hours with a forty-horser eating its head off! So here I am, on my way to the address you gave."

"It was plumb opposite Baumgartner's. I mounted guard there the very night you left. He came out twenty minutes ago, and your boy after him!"

"But what does it all mean, Thrush? What on earth were you doing there, my dear boy?"