CHAPTER XV

A TRIPLE TRAIL

Pulling Al further back out of the light, around the little dark jog beside the door jamb of the supply room, Bob put his lips close to his brother’s ear.

“Watch!” he whispered, hardly loud enough for Al to hear.

With a little squeeze to reassure his brother, Bob let go of Al’s arm and tiptoed back up the stairway, carefully clinging to the side wall and hoping that this precaution would enable him to get away without causing the steps to creak.

He was successful. Al, noting that the man inside the room seemed to be doing nothing more than standing there considering the layout of the place, guessed that Bob wanted to consult with Curt, watching upstairs. Al felt important: he was in the very heart of mystery, and much depended on him. Therefore he watched with every faculty alert as the man turned his head this way and that, apparently inspecting the stock of wing and fuselage cloth, the boxed instruments, the cases of “dope” for varnishing bodies and wings, the many other visible objects held in reserve.

Bob, slipping along the hallway at the top of the steps, noticed that both offices were lighted still, that both doors were closed, and as far as he could see, nothing had changed up above.

Curt was still watching. He was practically invisible in his nook by the water cooler. Bob, with a small word under his breath, reassured his comrade who came out of hiding as soon as he knew that the footsteps he heard approaching were Bob’s.

“Where did the stranger come from?” asked Bob softly.

“Stranger?” Curt’s voice betrayed amazement.

“The man who came down to the supply room!” Bob was also surprised.

“Was he a stranger?” Curt asked. “I thought it was Mr. Parsons. He came out of that dark directors’ room, beyond me.”

“Oh!” Bob clutched Curt’s arm in a tight grip. “Have you used your eyes, Curt, in daylight? If you have, you recall that there is a fire escape running up the side of the building—and the landing is by that directors’ meeting room window.”

“Is that so? Then, if that window is open——”

The opening of one of the lighted offices startled them, ended the consultation. Both comrades, tense, drew close against the wall behind the water cooler. If anybody was thirsty!——

The lighted square of that door went black. Someone had put out the dome light. Footsteps went carelessly along the corridor from the hiding youths, toward the front stairway.

“I must follow—whoever it is!” whispered Bob. “Curt, watch here. Al will watch that other man. It’s——”

“A triple trail!” gasped Curt. “Go on, Bob. Be careful.”

Bob agreed and tiptoed along to the stairway. By the time he got there he had no need for special caution, the lower door was closing.

Bob ran lightly down the stairs, crossed the entry below, cautiously peered into the yard, lighter just there by the arc over the office building doorway, and nodded to himself.

Griff was passing around the side of the building!

Cautiously Bob trailed him, allowing the partner’s son to get out of sight beyond the turn before he left the doorway.

Where was Griff bound? The main gates were across the yard and, as Bob knew, they were locked while the night man made his rounds of inspection among hangars and plant structures.

While Al watched his man in the supply room, while Curt hid, watching the lighted office door, Bob wondered what Griff was about. The young man did not go anywhere near or bend his steps in the direction of the main entrance but turned, with Bob carefully watching as he clung close in the shadow of the office structure, and went on around the building toward the private exit used by the officials. Being the son of Mr. Tredway’s partner, Griff had a key; but Bob could see, as he peered around the building, that the gate stood slightly ajar already.

“Will he go on home?” Bob wondered. “Had I better go back to Al?”

His thought was answered by Griff’s actions. He paused at the gate, seeming to inspect it. He was surprised to find it ajar, Bob decided. He held his place close to the office shadow and watched, as Griff looked around, inside and outside the fence.

Then, as though discovering something, Griff ran out of sight, leaving the gate as he had found it.

Instantly Bob ran across the small open space to the gate. There, in sudden caution, he cuddled his body close to the fence; it had just crossed his mind that Griff might have gone outside in a pretended hurry to draw out any pursuer; he might be hiding, watching!

He was not, however.

The sputter and roar of a motor startled Bob.

“That’s queer,” Bob mused, while he projected his head through the gateway. Almost in the same instant that he saw Griff starting up a motorcycle, Bob saw Griff shut off the motor and trundle the machine away.

“His own motorcycle is broken, since Saturday’s accident,” Bob reflected. “Now he must have brought another one. He meant to ride off in a hurry,” he deduced, “but he decided the noise would startle and warn people, so he’s going further away before he starts up.”

Instantly his own action was decided upon. He streaked back across the yard, around the hangars, to get his own bicycle. Against a speedy motor it would not keep Griff in sight, but it would enable Bob to get over the ground faster, and, if Griff did not go home, Bob meant to pursue him, making careful inquiries as he pedaled. There was only the crossroad for him to take, and Bob could see it from the highway.

In a very short time, and without having been seen by the watchman, Bob was out on the road. The distant sputter of the motorcycle engine and a speeding form passing the junction of the crossroads gave Bob all the information he needed. Without wasting energy in an effort to keep the flying cycle in sight, he pedaled after it.

The sudden sharp noise evidently startled others besides Bob.

Al, watching, saw the man who was evidently making some notes in the supply room, suddenly dash to the switch. Out went the light.

Al heard the scrape and rumble of a window being unfastened and thrown up. The man was listening, he judged.

Curt, by the water cooler, heard nothing but the faint sounds of the motor; at first he thought they were shots. When he saw the office light go out suddenly, immediately afterward, he thought someone in there had shot at some one else; but the door was flung open and he heard hurried feet pounding along the hall and almost stumbling down the front steps, careless of how much noise they made.

Curt could not go to explain to Al. He must see who that was going out of the quickly darkened office so swiftly.

Al needed no one to warn him. He crouched, tense and listening intently, outside the supply room door for a full minute. Absolute, torturing silence began to twitch his nerves. Nameless fears and countless uncertainties filled his mind. Was the man stalking him? Was he there at all? Had he ever been there? Was he human—or——?

Al heard a queer sound; at once he identified it. The window was being quietly pulled down.

Again he listened, watched, waited.

Curt, slipping down the banisters in the good, old-fashioned, speedy boys’ way, landed quietly at the foot of the stairs soon after the front doors of the office building closed.

But by that time whoever had emerged was far across the quadrangle and it was too dark to recognize him. There came the flare of the headlights of an automobile.

From its position on the grounds and from the style of its lamps, Curt guessed it was the runabout used by Mr. Parsons, Tredway’s remaining partner. What was he doing here? Where was he going? Curt, in the office doorway, not daring to emerge because of the beams of light that might swing around the yard at any moment, heard the voice of Parsons hailing the watchman, questioning him. The other replied in a way to show he had not heard any noises, could not account for them.

Curt, as the car got under way and the main gate was flung wide to permit it to depart, raced around the office building “ell” and across to his bicycle. He knew he could not pursue, but the wheel would give an excuse for emerging from that gate at once.

“Wait!” he called to the watchman, pedaling swiftly across to him. “I guess he forgot I was here,” pretending that Mr. Parsons sponsored his presence there so late at night. The watchman said nothing but held the gates open until Curt pedaled through and took his way after the car, not to keep it in sight but to see if it went to its owner’s home.

Al, ignorant that he was the only remaining member of the Sky Squad, watched tensely and listened alertly beside the supply room door. He heard nothing. Cautiously he protruded his head around the door jamb.

The room was silent, evidently the man was hiding or—“gone!”

“But how—where—could he go?” Al answered his own questions at once, for the window, made of tiny panes of thick glass between heavy bars, locked always from inside, impossible to open from outside, was not tightly shut.

For once in his life Al paused to think before he acted.

That window was not tightly shut. He had heard it opened, and—closed. But if the man had closed it from within the room he would have pulled it down tightly. He had not done so. He had left it partly open—why? To provide a way to come back, Al decided.

Almost at the same instant it flashed into his head that if he were to be caught in that room, with its door unfastened, he would be accused by any of the plant members, the watchman or those he thought were still in the upstairs offices, of stealing whatever might be missing.

He had a plan, at once!

He tiptoed back to the steps, listening. No sound came to him. Softly he went into the open doorway, made sure the window was not tightly shut, by inspecting the lighter space beneath it, then very quietly let the door go shut, allowing its spring lock to snap. He could open it from inside if he had to escape. No one without a key could open it from the hallway.

Then he ran close to the window, peered out, listened with an ear to the crack beneath the lower panes.

Nothing was stirring. But from the window he could see the gate, and the light was sufficient to show him a man’s form arriving there.

Evidently the form stopped from surprise or caution, then it went swiftly out. Al, forgetting fear, flung the window slightly upward, edged out, dropped to the ground, reached up and almost closed the window, then fully drew it down with a little slam, and raced to the gate. There he paused, peering out carefully.

Down the narrow lane he saw a man’s form trudging rapidly.

The third trail was opened!

After the man, at a distance, trudged Al!