III.

Lindy grabbed Nik’s arm. “Come on! There’ll be people here sure enough in a minute!”

They joined Heather outside and raced around the nearest dark corner. Sure enough, in a few moments they heard voices and saw people running toward the hangar. Nik recognized one of the voices as Linc Marshall.

“Lindy, how did that happen?” Nik whispered. “How did that plane get started?”

“I don’t know. Let’s listen for a moment. Maybe we can hear something.”

The men in the hangar lost little time killing the Avenger’s engine. The girls positioned themselves near a hangar door so that Lindy could listen through a crack in the doorway. “There are at least four voices in there. I recognize Marshall and Morrison. It sounds like they’re searching the plane and the hangar. Now somebody’s saying something about not being able to find a starter cartridge in the plane. Now they’re—come on, we’ve got to go! I think they’re about to come out here!”

The trio ran to the nearest other building. Using this and other structures for cover, they made their way back to the car. This took a little while, since they had gotten disoriented. Eventually Nik realized where they were and figured out how to get where they needed to go.

On the way back to Uncle Roy’s, Nik told Heather about Lindy’s climb. “Did you find anything up there?”

“Sure did, Heather. I found six objects that looked very much like oversized shotgun shells. I strongly suspect they were Coffman starter cartridges. Three of them were spent, three loaded.”

“And then the plane started up all by itself!” Nik added. “There was nobody in the hangar but us!”

“That plane must be haunted, then,” Heather wailed. “I’m not going back near it!”

“Somehow I don’t think a ghost would need to use Coffman starter cartridges to start the engine,” Lindy said calmly. “Nor do I think a ghost would need to hide them in such an odd place.”

“So how do you think they got up there?” Nik said.

“I got up there easily enough. I don’t think it’s an accident that frame was parked in just the right place to use it as a ladder to the rafter. I think somebody is sneaking in there and starting that engine. He’s keeping a ready supply of cartridges up there where there’s almost no risk of anybody seeing them.”

“You saw them!”

“Yes. But I wouldn’t have seen them if I hadn’t happened to look up at just the right angle. I doubt the mechanics in there have reason to look at the ceiling that often.”

“Well, we need to tell Uncle Roy about this.”

“Not just yet, Heather. I’d like to do a little more investigating first before we bring anybody else in on this.”

By the time they got back to the Nobel residence somebody from the airport had called to let Uncle Roy know what had happened. He felt so agitated about the latest incident that he did not ask too many questions about where the girls had been.

Lindy asked him an obvious question. “Could someone have started the engine by remote control?”

Uncle Roy sighed. “Linda, we’ve just about taken that aircraft’s instrument panel and electrical system apart looking for some secret remote controlled starter device. There’s nothing in there that doesn’t belong. I’m sure Linc is probably going over the whole thing once again trying to find something wrong even as we speak.”

“Who discovered that the engine had started?”

“A couple of people seem to have heard it at about the same time, from different places. Linc got there first. Another mechanic, Bill Pearson, and Walt Carter the pilot got there right after him.” Uncle Roy sighed again. “There’s not much point in spending a lot of time on it tonight. I’m going to turn in soon. I’ll need a good night’s sleep for tomorrow!”

Uncle Roy left for the airport early the next morning to begin preparations for the air show. The guests lounged around the house until mid-morning, when Aunt Jenny arrived home from her visit to family out of town. A somewhat gushy lady, she made a huge to-do over Heather and her friends.

After she had gotten settled in, she insisted on taking Heather, Lindy, and Nik shopping. Soon they were off, leaving the guys to make their way to the airport to view the air show preparations. Nik mainly went with Aunt Jenny out of politeness. Heather of course loved the chance to shop and visit with her aunt. Lindy liked the shopping expedition herself—she did have an interest in clothes! She ended up buying a new scarf, a red one to match her hair. Lindy and her scarves, thought Nik! She always had a scarf around her neck.

After lunch and a couple of hours of shopping, Aunt Jenny took them to the airport to see how the work was coming. Uncle Roy and his crew were getting the planes lined up outside for the next day’s static aircraft display. He had roped Glenn and Jack into assisting with the airplane handling. They did not seem to mind!

Heather and her friends had the run of the place, as long as they stayed out of the way. Lindy took full advantage of this. She walked around the planes. She observed the mechanics and pilots going back and forth. She peeked into the work shop where the Avenger had sat. And she took a closer look at the Avenger itself.

“You know, I’ve realized something,” she told the others, as they stood beside the A-20 a short distance away. “The Avenger is a three-seat aircraft with a bomb bay. There’s enough space for a person to hide in there without our being able to see him in the cockpit unless we took a close look.”

“Are you saying there might have been someone hiding in there last night while we were in the hangar?”

“Exactly, Nik. We never really looked in the cockpit. We just assumed since we did not see anybody’s head in the canopy that there was nobody there. It’s entirely possible that we walked in just as the saboteur was preparing to start the engine. He hunkered down and waited while we were there.”

“Then he probably heard everything we were doing in there!”

“Very likely. That would explain why when I looked up at the rafters a little while ago I didn’t see the Coffman cartridges. He probably went up there and moved them to another hiding place.”

“Well, there goes our evidence!”

“Yes. Unfortunately!”

Heather looked over at the Avenger. “You mean instead of a ghost there was somebody in that plane all the time we were there? That’s even creepier!”

Nik looked at the silent aircraft as well. “Why did he start the engine while we were in there? Wasn’t he taking a chance that we’d find him?”

“The engine started right after Heather called out that she thought she saw somebody coming. Maybe it was a desperate move to scare us off and give the culprit a chance to slip out before the others got there.”

“But there’s no way he could have gotten out of the hangar in time to keep people from seeing him.”

“I don’t think he had to get out of the hangar. He just had to get out of the plane. That work area has a lot of large pieces of equipment and barrels and so forth that a person could hide behind. Everybody would have been so busy paying attention to the plane he could have slipped out behind them. Or just stayed hidden. It’s even possible he stood out in the open and pretended to have gotten into the shop before anyone else did.”

Heather’s eyes grew wide. “You mean Linc Marshall! He’s the one who got to the plane first last night!”

“It’s certainly possible.”

Lindy began to walk away from the row of aircraft. “Come on, there’s something else I want to check.”

“What?” asked Nik.

“The crew’s personal vehicles. There’s been a lot of moving to and fro over the last couple of days. I’ve noticed who drives what in several cases. We might be able to learn something from reading cars.”

Nik had seen Lindy “read” cars before. She believed that you could tell a lot about people from what they drove. Nik and Heather followed Lindy as she inspected several nearby vehicles. Some were old and beat-up. Some looked new and nice. All of them contained tools and other paraphernalia of some kind. One or two even had reading material. “Can you make out the cover on that book?” Lindy asked Nik, as the peered through the window of one SUV.

“I think it’s a book on guns. No, it’s a book on loading shotgun cartridges.”

“Interesting….”

By the time it got dark the workers had organized all the aircraft in the display. “Okay, everybody, I think we can knock off for the evening,” Uncle Roy announced. “I want all pilots to get a good night’s rest. We’ll all need to be fresh tomorrow if we’re to give the public a good show!”

The workers drifted over to their vehicles and left. Uncle Roy collected all of his family and visitors. “All right, let’s everybody go out to eat. I know Aunt Jen’s bound to be tired after all her activity. And I’ll be too busy tomorrow to take everybody out then.”

Heather took a last look at the row of vintage aircraft as they left. “Are the planes going to be okay sitting out there like that?”

“They’ll be fine! There’s no bad weather in the forecast. We’ll have a watchman patrolling the line-up. The planes are perfectly safe.”
Somehow, Nik did not feel from his voice that he sounded completely certain of this. She was not so sure the planes would be all right either.




IV.

After they got back to Uncle Roy and Aunt Jenny’s house, Heather and her aunt and uncle settled in for a quiet evening of visiting. At Lindy’s suggestion she, Nik, and Jack announced that they were going for a drive to see the night life. “Not much of that around here, but okay,” said Uncle Roy. Glenn, to nobody’s surprise, stayed behind with Heather.

“That one watchman can’t keep a good enough eye on all those planes at the same time,” Lindy said, as Nik drove them to the airport. “And the mechanics who will be on duty making last-minute preparations will be too busy to keep a good watch. If somebody really sneaky who knows his way around wants to gain access to one of them, he’ll be able to do it. So we’re going to keep an eye on the Avenger ourselves.”

“We can’t stay there all night,” Jack pointed out. “Heather’s uncle will get suspicious if we’re gone more than a couple of hours.”

“I did some checking with Uncle Roy. Every mysterious engine starting incident occurred before ten at night. There were always mechanics working nearby. I think our `ghost’ wants an audience.”

“How are we going to keep people from wondering what we’re up to?”

“We’ll just have to be very quiet and unobtrusive ourselves, Jack. And I do mean quiet!” Lindy shot Jack a significant look.

As Lindy had predicted, people at the airport were too busy to pay any attention to their car as they pulled onto the field and drove to the older section. They parked the car in the usual parking area next to one of the aircraft taxiways. There were just enough vehicles there to keep the car from standing out too badly.

Carefully and quietly they made their way to the aircraft line-up. They took up a position behind a couple of barrels sitting beside a hangar’s side wall. From here they could see the Avenger without being seen. The moon, stars, and artificial lights gave them enough light to spot anyone going over to the plane.

Nik pressed the little night-light on her watch. “Nineteen minutes after eight.”

“How long are we going to be here?”

“Until ten at the latest,” whispered Lindy. “Now please, Jack, be quiet!”

About an hour into their watch they spotted somebody approaching the Avenger. Nik strained her eyes to make out who it was. The light and distance were just a little too great. The figure stood on one side of the engine cowling and appeared to be doing something. Was he loading a starter cartridge?

Lindy grabbed Nik’s arm. Nik turned and looked Lindy in the eye. Neither said anything. Lindy nodded her head. Nik realized that Lindy must have guessed her question. Lindy thought that this was their man as well.

The man now climbed into the Avenger’s cockpit. A few more moments passed.

Then Nik heard the high-pitched mechanical whine she had heard when the engine had started the night before.

Lindy started to scramble to her feet. “He’s starting the engine! We’ve got him!”

The engine coughed and came to life. Nik, Lindy, and Jack forced their cramped legs to move and ran toward the plane.

As they approached the aircraft, the engine’s rumble rose to a roar. The plane began to roll across the ground. Nik and the others scrambled to avoid its wings. The Avenger turned and began rolling down the taxiway.

“He’s headed for the runway!” Lindy cried. “Run for the car! We’ve got to catch him!”

Nik and Jack obediently followed Lindy in the direction of the car. By now men had begun to appear from the nearby hangars. They began pursuing the plane on foot. Nobody seemed to notice Lindy and company.

Nik and Jack pulled ahead of Lindy and reached the car at the same time. Nik pulled the car key out of her pocket, threw open the driver’s side door, slid into the seat, and started the engine. The others scrambled into their seats.

“Drive down the taxiway after him!” Lindy ordered.

“Lindy, there’s no way we’ll catch him before he takes off!” Jack said.

“He won’t take off! Go, Nik!”

Nik pulled onto the taxiway and raced after the plane, driving as fast as she dared. The men who had been chasing the Avenger on foot scattered at the car’s approach. They had already fallen well behind the runaway plane.

By now the Avenger had reached the runway. It turned to face down the runway’s length. Over the noise of the car’s engine Nik heard the huge Wright power plant’s full-throated roar grow in volume and pitch.

“He’s revving for takeoff!” Jack shouted. “We’re sure never going to catch him!”

“He won’t take off!” Lindy insisted. “Keep after him!”

The Avenger began traveling down the runway. Nik spun the wheel and pulled the car onto the runway after it. As the planed rolled faster, Nik gave the car all the gas it had. The plane kept pulling away. Jack was right. They would never catch that plane!

Suddenly Nik realized that they had begun gaining on the aircraft. It was slowing down! The Avenger rocked violently from side to side as it braked to a stop almost at the end of the runway. The car’s tires squealed as Nik frantically hit her own brakes. She came to a stop within a few yards of the aircraft’s right wingtip.

A man sprang from the cockpit, lighted on the wing, and leaped to the ground. He began running toward the fence on the edge of the airfield. Nik, Jack, and Lindy climbed from the car and ran around the plane after him.

Though the runner had a good head start, he did not seem to be much of a runner. Jack was already gaining on him by the time he reached the fence, with Nik and Lindy not far behind. Jack caught up with the fugitive and grabbed him around the waist as he struggled to climb over the fence. The man struggled, trying to kick back at Jack. He could not fight very well while still trying to climb.

Now Nik got to them and began tugging on one of the man’s arms.

Lindy seized the other arm. The climber lost his grip. All four of them tumbled to the ground. For the next few moments the man struggled to rise, as the others piled on top of him.

He abruptly went limp. “Okay, okay, I give up!” he cried.

The others kept him pinned. “All right,” growled Jack, sounding as tough as he possibly could. “We’re going to let you stand up. Get your hands over your head and face the fence. You got that?”

“I got it, I got it!”

They carefully released the man and stood up. He did exactly as instructed.

Nik glanced up the runway. She saw a pair of headlights racing toward them. “Hey, there’s a car coming this way!”

Actually it turned out to be a pickup truck. The truck lurched to a halt near the aircraft and the car. Three men scrambled out. “What in the world is going on here?” one of them demanded. It was Linc Marshall.

“We’ve just caught the ghost that has been haunting this aircraft,” Lindy announced. “Jack, have him turn around.”

“Okay, turn around!” Jack growled.

The man turned, his hands still above his head. Linc Marshall strode over to him, a large flashlight in hand. By the beam they saw the frightened face of Chad Morrison.


V.

Uncle Roy had to spend a good part of the night talking to the police and getting the Avenger towed back to its hangar. He and the police agreed to keep the plane in the hangar and out of the next day’s air show activities. For one thing it potentially held evidence. For another, Uncle Roy feared that something might now be wrong with it, and did not really have the time to give the aircraft another thorough check.

Apart from the Avenger’s absence from the program, everything went very well at the air show the next day. The weather was clear and fairly warm. A sizeable crowd came to view the old aircraft, see some of them fly, and watch an out of town stunt flying team go through their paces.

When the show ended Aunt Jenny took Heather and her friends home. Uncle Roy had to stay for several more hours to help get things squared away at the airport. By the time he got home the others had prepared a late supper for everyone. Tired though he now felt, he had to question Lindy about the investigation. Lindy described everything that she, Nik, Heather, and Jack had done since the beginning.

“I still can’t believe you suspected Linc,” Uncle Roy said in the middle of the story. “Linc has his bad moods, but he has always been as trustworthy as anybody I know.”

“We didn’t have the benefit of knowing Mr. Marshall,” Lindy pointed out. “All we knew was that he seemed to have motive, means, and opportunity. He appeared to be your rival, he knew how to produce starter cartridges, and he had ready access to the plane. Mr. Marshall also seemed usually to be the first to reach the plane after every mysterious starting incident. That suggested that he might possibly be starting the engine when nobody else was looking and then pretending to be the first to discover it.

“We did suspect Chad Morrison to some extent. He had access to the aircraft as well. He moved a lot higher on my list when Nik and I inspected the crew’s parked vehicles and discovered a book on loading shotgun shells in one of them. I observed Morrison driving off in that vehicle a little later. That suggested that he had an interest in learning a skill that might help him to start the Avenger’s engine. Mr. Marshall would not have needed to read up on loading shells, because he already knew how to do it.

“The more I thought about it that evening, the more likely a suspect Morrison seemed. Mr. Marshall always inspected the aircraft after every mysterious engine start. But Morrison always seemed to go over it after Mr. Marshall had made his check. Perhaps this was Morrison’s way of getting someone else to see that the plane was in good condition, prior to his sabotaging it. After the plane had experienced its technical problems, he could then arrange to reverse the sabotage and make it look like nothing had ever been wrong with the plane. All this made the whole business more mysterious and eerie.

“By the time we staked out the plane, I had pretty well made up my mind that Morrison was our man.” Lindy turned to Jack. “That’s why I was so sure the fugitive would not take off when he got to the runway. Linc Marshall is a pilot. Chad Morrison isn’t. He was just trying to get ahead of his pursuers so that he could escape on foot.”

“Why in the world did he do all that stuff, though?” Heather wondered.

“I can tell you that now,” said Uncle Roy. “During the air show the police kept trying to call me. I finally made some time to speak with them. After a night in jail, Chad Morrison confessed that he had been behind all the problems with the Avenger. He said that Clyde Cartwright, the aircraft collector, hired him to do it. Apparently Cartwright was even more upset than we thought at our buying the aircraft before he did. Morrison had worked for Cartwright for a while before he came to us. Cartwright knew that Morrison had a way of burning through money—and would do just about anything to get more if he got the chance.”

“I guess he figured that making the plane look jinxed would cause your foundation to be more willing to sell it to him eventually,” Lindy said.

“Yes. Morrison confessed that he was planning to sabotage the electrical system again. He had confidence that Walt Carter would again be able to bring the Avenger down safely. He figured a close call like that at an air show might just convince us that the Avenger was more trouble than it was worth it.

“It was a crazy scheme! And dangerous! You can’t mess around with aircraft. Even the sort of slight sabotage he was performing could have unintentionally led to something very serious. Much as I hate losing a proficient mechanic, at this point I have no sympathy for the man. I’ll see to it that the foundation prosecutes Morrison and Cartwright to the fullest extent of the law!”

Uncle Roy now gave Lindy and the others a look. “Speaking of laws and rules, you do know that driving on an airport runway, while an aircraft is using it, is a definite no-no, don’t you?”

“I kind of guessed that might be the case,” Nik admitted. “But we had to catch that plane!”

“Yes, you did. Which is why even though I should probably be very angry at you over this business, I can’t quite bring myself to do it. I owe all of you a lot of thanks.”

Heather patted Lindy on the arm. “Mostly you owe Lindy thanks. She’s our detective!”

Lindy’s face reddened a bit. “I guess our group has a talent for finding mysteries.”

“I’m not sure I like that talent,” said Heather.

Jack put his arm around both Heather and Lindy. “Hey, don’t knock it. It makes life interesting!”