They parked the truck half a block beyond it and hurried back. Joe quickly scrutinized the premises. Then he assigned Chet to guard the rear door, while he himself would watch the front.
“If Lieber has our camera hidden in his apartment, he may sneak it out,” Joe told him, “so keep your eyes open.”
“Okay,” Chet answered. “Say, this kind of work sure can give a man an appetite,” he hinted.
Joe knew that once his chum had felt the pangs of hunger, it was hopeless to try taking his mind off food. It took little prompting to send Chet rushing off to get both of them something to eat.
The young detective watched both the front door and the service alley of the apartment house. No one came out, and it was not long before his stout pal reappeared carrying sandwiches, cartons of chocolate milk, and fruit.
He handed Joe an apple. “This will do for an appetizer,” he announced.
Chet then divided the rest of the food and carried his portion down the narrow alleyway to take up his post at the rear door of the building.
Actually, Chet found two doors there. One was located at the top of a short iron stairway and led into the first floor of the apartment house.
The second, which obviously led to the basement, was situated directly below the other. Chet looked around and selected a vantage point in the shadow of an adjacent building.
“Guess nobody can see me here,” he thought.
As Chet began munching on his third sandwich, his eyes suddenly focused on the upper door. It was, he realized, being eased open. The figure of a man carrying a large package under his arm slowly emerged. Closing the door quietly behind him, he crept down the stairway.
“The camera!” Chet decided.
He bolted from the shadow of the building. The man spotted him immediately. Startled, the stranger turned and broke into a fast run up the alleyway coward the street. Chet took off after him, still holding his sandwich and carton of chocolate milk.
The distance between Chet and the man he was pursuing rapidly closed. In desperation, the stranger stopped and whirled about. Chet was caught off guard.
“Youâyouâ!” the man hissed at him.
Holding the package with one hand, he reached out with the other and wrenched the carton of milk from Chet's grasp. Then he threw its contents full force into the boy's face!
“That'll teach you!” the man snarled.
Chet was blinded by the deluge. He stood sputtering, vigorously wiping the liquid from his eyes. By the time he could see again, the man had disappeared.
In disgust Chet dashed out of the alleyway and around to the front entrance of the apartment house, to warn Joe. No one was there! The farm truck was gone.
Chet was in a quandary. Not only had the stranger disappeared, but so had Joe!
“Perhaps,” Chet thought, “Joe spotted the man running from the alley with the package and drove after him. I sure hope so.”
The stout boy took up a position across the street from the apartment house. From there, he could watch for Joe and guard the front of the building at the same time. The only people he saw come out were two women carrying small handbags. He observed nothing suspicious.
Finally Joe pulled up in the truck and hopped out. Chet ran to meet him. “I was beginning to worry,” said the plump boy. “Where did you go?”
“That'll teach you!” the man snarled
“While watching from here, I saw a man running out of the alley,” Joe answered. “He was Lieber! Before I could catch him, he jumped into a car parked up the street. I chased him in your truck, but I got mixed up in a traffic jam and lost him.”
Chet told Joe about his encounter with Lieber, and pointed to his chocolate-stained clothes. He apologized for having been caught by surprise.
“It couldn't be helped,” Joe excused him. “The car that Lieber jumped into was waiting for him, I'm sure. I managed to get the license plate number. We can check it out tomorrow with the motor vehicle department.”
By now the boys were convinced that there was little to be gained by continuing to watch the apartment house, so they decided to go home.
“What do you think Lieber was up to?” Chet asked as they rode through the Bayport streets.
“I don't know,” Joe responded. “But whatever it was, he certainly wasn't wasting any time.”
“Do you think that was the camera he was carrying?” Chet questioned.
“Yes. Some pal might have sneaked it from the airport to Lieber's place. We have no proof, though.”
Chet stopped at the Hardy house and dropped Joe off. Then he sped for home, his face beaming with anticipation of the hearty meal he knew would be waiting for him.
Joe was about to enter the house when he saw Frank turn into the driveway. “Hil” he called.
“Did you just get back?” Frank asked as he climbed out of the convertible.
“Yes. Did you have any luck following Zimm?”
“Enough to make me more suspicious of him,” Frank replied. “I'll put the car in the garage and then let's talk.”
In a few moments the boys went into the house. Mrs. Hardy and Aunt Gertrude were relieved to see them, since it was long past dinnertime.
“You must be starved,” Aunt Gertrude remarked. “And besides, the food's half ruined, standing here for over an hour!”
Mrs. Hardy smiled. “I don't think the boys will mind.”
The boys did not mind. They found the roast lamb, mashed potatoes, peas, and strawberry short-cake delicious. All the Hardys laughed over Joe's description of Chet's encounter with Lieber and the chocolate milk.
After dinner the brothers joined their father in his study. Frank was the first to tell his story, then Joe. Mr. Hardy listened with great interest.
“You say the man who knocked you down wore a mask?” he asked Frank.
“Yes! And if he was a ghost, he was a pretty solid one! By the way, Peterson has asked us to find the ghost! Shall we take his case?”
Mr. Hardy thought for several seconds before answering. “Yes, take it. This so-called ghost seems to bob up a good deal. He's worth pursuing.”
The detective and his sons also agreed that the mysterious behavior of Zimm and Lieber could not be coincidence. It must be linked with the case, and the two were working together in some sinister plot.
Mr. Hardy warned his sons that they should be extra careful. “If Zimm and Lieber are involved in the platinum thefts, and think you suspect them, they may make it sticky for you.”
“We'll try not to flub again,” Frank promised.
“What do you plan to do next?” their father inquired.
“I'd like to drive out to Zimm's house tomorrow' morning,” Frank replied, “and investigate the area. We might be able to come up with a clue or two.”
“Good idea. I'll keep on investigating at Stanwide itself.”
Early the next day Frank and Joe drove to Zimm's house and cruised slowly past it. They saw that the garage, in which Zimm kept his car, was empty, and surmised that he had already left for work. The boys parked their car on the next block, then walked back toward the house. They tried to act nonchalant.
“That's where I ran into the masked stranger,” Frank said, pointing. “You investigate that side of the house, and I'll reconnoiter the grounds.”
Frank scanned the premises carefully, inch by inch. He saw the area of ruffled grass where he and the masked stranger had tumbled in their struggle. Unfortunately, even his trained eyes failed to detect a single clue.
As Frank continued the examination, his brother suddenly spotted something which startled him.
“For Pete's sake!” Joe exclaimed.
CHAPTER X
Startling Discoveries
FRANK rushed over to Joe. His brother was staring at something in a flower bed. Frank glanced down and was astonished at what he saw. There, deeply impressed in the soft dirt, were two footprints.
The instep of the right foot was narrower than that of the left. The prints appeared to be duplicates of those the boys had discovered in the concrete floor of the Stanwide hangar.
Clint Hill's footprints!
“What do you make of it?” Joe asked his brother excitedly. “Could Clint Hill be alive?”
“The reports certainly don't indicate it,” Frank replied. “But if he is, why would he be sneaking around like this?”
“I wonder if the whole thing is a hoax,” Joe said. “Maybe Lance Peterson is using us to cover up a crooked deal he and Hill are involved in. They feel safe because they didn't count on our picking up the footprint clue in the hangar. Someone tried hard to keep us from seeing the prints. Maybe it was Hill himself!”
Puzzled, the boys decided to have another talk with Peterson. As they were about to leave, a window in the house was flung open, and a woman poked her head out.
“What are you doing here?” she shouted.
Startled, the boys looked up. “We wanted to see Mr. Zimm. Is he at home?” Frank replied coolly.
“Then why didn't you come to the door, instead of prowling around out there?” demanded the woman in a rasping, unpleasant tone. “I'm Mrs. Zimm. What do you want with my husband?”
The Hardys realized that they could not reveal to Mrs. Zimm their reasons for being there. Perhaps she was in the plot with her husband! On the other hand, she might not know anything about his mysterious behavior, nor have heard any talk about Clint Hill's ghost. In that case, the boys did not want to upset her.
“We're working on a job for Lance Peterson,” Joe ad-libbed, “and we wanted to ask Mr. Zimm some questions.”
“He left for work about an hour ago,” his wife said indignantly.
“Then we'll see him there,” Frank told her.
She demanded that the boys leave at once. Glad to get away, they did not argue and returned to their car. Frank started for the Stanwide hangar.
“I could see by her face that Mrs. Zimm didn't know whether to believe us or not,” Frank commented.
Joe agreed. “I hope that when she tells Zimm we were here, it doesn't put him on guard.”
“It won't make much difference one way or the other,” Frank observed. “Either Zimm knows we suspect him of somethingâwhich means our prowling around wouldn't surprise himâor else he might really believe we came out to ask him some routine questions.”
When the boys arrived at the airport, they went at once to the Stanwide hangar. Lance Peterson's office door was locked. As Frank and Joe strolled back across the hangar, they saw Jerry Madden come out of the operations room.
“I've got a message for you!” he called to the Hardys. “Mr. Allen has been trying to find you. He wants you to call him right away.”
Frank asked Jerry if he knew where Peterson had gone. Jerry said No, Peterson had taken the day off. Frank went to telephone Mr. Allen.
“We are sending a large shipment of parts containing platinum to the Sun-Plat Tool Company in California tomorrow morning,” the executive told him. “Our company cargo plane will make the delivery. Lance Peterson and Aaron Lieber will be flying it. Because of the great value of this shipment, and the trouble we've been having, as an extra precaution I would like you boys to follow in another plane. Can you do it?”
The Hardys excitedly agreed. “Don't worry about arranging for a pilot and planeâwe'll handle that ourselves,” Frank said.
A short time later he and Joe were in the operations room of Ace Air Service, discussing the trip with Randy Watson.
“The Stanwide cargo plane is a pretty fast ship,” Randy said. “We don't have any equipment at Ace that would keep up with her. I'll have to lease a special plane.”
“Go ahead and make the arrangements,” Frank told him. “But keep it quiet.”
On the way home the Hardys stopped at police headquarters to ask them to check the license plate number of the car Joe had seen Lieber jump into. Detective Lieutenant Obels, a determined but pleasant man, sent the number to the motor vehicle department by police teletype. In a little less than an hour Lieutenant Obels called the boys at their home.
“Here it is!” the officer announced. “The report says the car belongs to a Mr. Art Rodax.”
Frank thanked the detective, then hung up. “Art Rodax, our former boss!” he exclaimed, repeating the news to Joe.
“Good night! He's a pal of Lieber!” Joe cried out. “Well, we're rounding up quite a group of suspects!”
Hoping to turn up another clue, the boys began calling all the camera stores listed in the telephone book. Not one of the shops reported having seen the stolen camera.
At five oâclock Mr. Freeman called Frank. The camera-shop owner said that the developed pictures had just arrived. “Mr. Williams, the name under which the pictures were left, has already telephoned that he's coming by for them.”