An hour and a half later Jack Wayne and the boys were cleared for an ILS approach at Logan International Airport.
“Looks as if the weather's beginning to improve,” Jack remarked as they taxied to the parking ramp.
“I don't see the helioplane anywhere,” Joe observed.
“We'll check with operations,” Frank said.
The boys hurried into the administration building. They located the operations manager and inquired about the helioplane.
“Why, yes,” he said. “I remember the craft distinctly. It caught my eye, since that kind of thing is a rarity around here.”
“Where is it now?” Joe asked.
“I think it took off about thirty minutes ago,” the operations manager replied. “But why don't you check with the control tower?” He pointed to a wall telephone. “That's a direct line.”
Frank picked up the phone.
“Logan Tower! Stigand speaking!” crackled from the receiver.
Frank said, “A helioplane departed from here about half an hour ago. Can you tell me its destination?”
“Stand by!”
There were a few seconds of silence, then Stigand reported, “The pilot filed an instrument flight plan for Concord Airport, New Hampshire. However, he broke into clear weather at Manchester and canceled his flight plan.”
“Thank you,” Frank replied, dejected.
“So we've lost them again,” Joe remarked.
“Timken and his pilot played it smart,” Frank said. “They knew they'd fly into clear weather. I'll bet they never had any intention of landing at Concord.”
Just then two men approached the youths.
“What's your interest in the helioplane?” one of them demanded.
“Who are you?” Joe retorted.
“We're detectives! Boston Police Department!” They flashed their badges.
“My name is Amory,” one said. He pointed to his partner. “And this is Detective Sergeant Doran.”
Frank introduced himself and his companions.
“Hardy!” Amory exclaimed. “Any relation to Fenton Hardy the private detective?”
“We're his sons,” Joe answered.
“Why did you ask us about our interest in the helioplane?” Frank inquired.
“A couple of hours ago a local jeweler was approached by a fellow who tried to sell him a diamond. When the jeweler began to question him as to where he got it, the guy walked out. The jeweler became suspicious and called us.”
“What started you looking for this man at the airport?” Joe asked.
Amory replied, “The jeweler said he was wearing a Great Circle Airways uniform. So the airport seemed a logical place to begin a search, although Great Circle doesn't come in here. We want to ask that fellow a few questions.”
“He's gone,” Frank said. “The man you're looking for is the same one we've been following. He took off in the helioplane about half an hour ago.”
“That adds up,” Doran commented. “The operations manager told us a fellow answering the jeweler's description had already left.”
“We approached you boys,” Ames added, “because we heard you inquiring on the phone about the helioplane.”
There was little more the young sleuths could do, so they took off. During the return flight to Bayport, they mulled over the latest event.
“What do you make of Timken trying to peddle a diamond?” Joe asked.
“It sounds to me like an attempt to get rid of stolen goods,” Frank concluded.
“Could be,” Joe said thoughtfully. “You remember Dad's report said that Hexton's gang were robbers. If Timken is one of them, he may be smuggling in jewels stolen overseas and disposing of them here.”
Frank agreed. “But UGLI's business is espionage. I doubt if they would become involved in jewel robberies. On the other hand, Hexton and his gang might be playing the two games at once.”
When the boys arrived home, Frank at once telephoned their suspicions to Kenneth Dell.
“You have a good theory there,” Great Circle's security chief said. “I'm going to call Scotland Yard and inquire about recent jewel robberies.” He promised to get in touch later.
After Frank hung up the phone, he stood silent for a moment. “Next we
must
figure out that message Dad left on the hotel wall,” he told Joe.
Again they examined the row of numerals: 441810682300. But after more than an hour of attempting to decipher them, Joe gave a sigh of frustration. “It doesn't make any more sense to me now than when we first started,” he admitted.
“If this is a code, it's a real puzzler,” Frank agreed. “But we've
got
to crack it!”
When Mrs. Hardy announced that dinner was ready, the boys reluctantly interrupted their task. They ate quickly, then went right back to the message.
Frank stared at it. “Neither the substitution nor transposition ciphers jibe.”
The young detectives worked late into the night. Exhausted, they finally went to bed.
Early the next day Frank and Joe continued to study the message, but all their efforts to decipher it ended in failure.
Shortly after ten o'clock Chet arrived at the Hardys' home. He plodded up the stairs to the detective's study.
“You're too late for breakfast, chum,” Frank said with a grin.
“Aw, cut it out,” Chet mumbled. “Anyway, I stopped at Biff Hooper's house before I came here. His mother was baking the most delicious pancakes I ever saw, with sausages and all the trimmings.”
“Glad to hear that,” Joe said jokingly. “We wouldn't want to see you fade away.”
“How is Biff?” Frank inquired as he glanced at his friend. Biff Hooper was a schoolmate of the boys at Bayport High.
“He's just fine. I wanted to show him a couple of my magic tricks.”
“Don't tell us you took that silver bowl of yours along?” Joe asked.
“No, that's old stuff,” Chet retorted. “My new tricks are more sophisticated.”
“Oh yeah!” said Joe, chuckling.
“Go ahead and laugh if you want to,” Chet continued indignantly. “At least Biff appreciated the great latitude of my genius.”
At Chet's remark, Frank sat bolt upright in his chair.
“What's the matter?” Chet asked, startled.
“Would you repeat what you just said?” Frank asked excitedly.
“You mean about Biff's appreciating the latitude of my genius?”
Frank sprang up. “The key! You've given me the key!”
CHAPTER VIII
Sailing Sleuths
CHET looked confused. “What key? I don't see any key,” he said, glancing around.
“You mentioned latitude! That must be itâlatitude and longitude!” Frank pointed to the numerals in the mystery message.
“I still don't get it,” said Chet.
Frank explained. “Notice that there are a total of twelve digits. The first sixâ441810âmust mean 44 degrees, 18 minutes, 10 seconds of latitude. The remaining figuresâ682300âwould then stand for 68 degrees, 23 minutes, 00 seconds of longitude ”
“You're right!” Joe exclaimed.
Frank riffled through a stack of maps and selected one showing the Atlantic seaboard. “Those coordinates would locate a position in the area covered by this map.”
“Hold on!” Joe said as he glanced at a chart of the world that he had just unfolded. “The message doesn't specify whether the latitude is east or west, or the longitude north or south. Therefore, these coordinates might designate a location in Asia, the southern tip of South America, or the middle of the Indian Ocean.”
“True,” Frank agreed. “But since Dad didn't make that clear in the message, I'm certain he means the position is in our own hemisphere.”
He marked the spot on his map indicated by the coordinates. It was about eighteen miles off the northeast coast of the United States.
“But that's a spot in the Atlantic Ocean!” Joe exclaimed.
Frank pulled out a nautical chart. It was on a smaller scale and showed more detail. Replotting the position, he discovered several small islets in the vicinityâso small they did not have names. The latitude and longitude coordinates lay directly over one.
“Eureka!” Joe exclaimed. “It looks as if we're onto something! My guess is one of two possibilitiesâeither the place is UGLI's headquarters for the U.S., or else it's where Dad was taken.”
“Maybe it's both,” Joe added. “We'd better make a trip to that island!”
“What about me?” Chet demanded. “Can I come, too? After all, I found the key!”
Frank bowed toward his chum. “It'll be a pleasure to have you along, genius,” he said. “We might need your help.” Then he walked to the telephone. “I'll call Jack and tell him to have the plane ready tomorrow morning.”
When Frank told the pilot their destination, Jack assured him there were several aviation radio facilities in the vicinity that would permit them to pinpoint the islet from the air.
Early the following day the Hardys, Chet, and Jack were winging their way toward the mystery spot. Soon they paralleled the Atlantic coast.
“How long do you estimate it'll take us to reach the place?” Frank asked Jack.
The pilot checked the bearings indicated by the radio compass and omni-navigation receiver, then thumbed his small computer. “I'd say about thirty minutes from our present position.”
The boys gazed below. Ocean waves broke against the craggy coastline, tracing it with a ribbon of white foam that stretched as far as the eye could see.
As they passed over a small sailboat, Joe took out binoculars and scanned the area below. “Little islands ahead,” he announced, and soon the others made out small sprinkles of land dot-ting the surface of the water.
“According to the cross bearings I calculated,” Jack announced, “we should be over the place you want within one minute.”
“And what exactly are we looking for?” Chet queried.
“I don't know,” Frank answered. “But ifâ”
“Hey!” Joe interrupted. “I see a lighthouse on that islet just below us.”
Frank took the binoculars. “You're right. It appears to be abandoned, but there are several cylindrical-shaped objects just to the left of the lighthouse.”
Jack took the plane to a lower altitude and Frank readjusted the glasses. “They look like drums of oil, or gasoline,” he said.
“But for what?” Joe questioned. “A boat? Certainly couldn't be for an airplane.”
The pilot asked for the binoculars and studied the islet. “The surface is level enough for a plane,” he observed, “but it's much too short to be used as a runwayâthat is, except for a helicopter, or perhaps a helioplane!”
Frank and Joe glanced at each other. Could there be a connection between the islet and the helioplane in which Timken had eluded them?
Frank suggested they fly back to the coast and land at the nearest airport. “I want to find out about the islet,” he said.
Jack found a small field not far inland and set the plane down. The Hardys hopped out and hastened to the operations shack. There they met a solid, middle-aged man with a shock of gray hair, who introduced himself as Ty Carter, the owner of the airport.
“I don't know much about that islet with the abandoned lighthouse,” Carter told them, “except that it is private property. It was sold at auction recently.”
“Have you any idea who bought it?” Joe asked.
“Fellow named Bodkins. He's not from around here so I can't tell you anything about him.”
“Bodkins?” Frank thought. A possibility struck him. “Could this be an alias of Hexton's?” Aloud he questioned, “Have you ever seen a helioplane in the vicinity of the islet?”
“Funny you should mention that,” Carter replied. “During the past couple of weeks I saw one headed in that direction several times. But whether it was going to the islet or not, I wouldn't know.”
The boys thanked the man for his cooperation, then returned to the plane.
“Fellows,” Frank said suddenly, “I have an idea. Why don't we rent a boat and look at the place?”
“What if Hexton and his men
are
on the islet?” Chet asked.
“That's a chance we'll have to take.”
After lunch Jack remained with the plane, while Chet and the Hardys hiked to the nearby coastal town. They found a boat-rental place, but unfortunately all the power craft were in use. Frank finally selected a small jib-headed racer.
He manned the helm while Joe and Chet hauled the sails to the top of the mast. A strong breeze carried them quickly away from the dock. Nearly three hours passed before the islet appeared off the port bow of their craft.
“Seems deserted,” Joe said.
Frank manipulated the helm to direct the boat in a wide circle around the tiny point of land. From the other side of the islet a fast powerboat appeared.
When it drew closer, Joe exclaimed, “That's Stony Bleeker at the wheel! And Vordo's with him. They must have spotted us!”
“The boat's going to ram ours!” Chet shouted as the craft headed directly for the sailboat.
Frank applied hard helm and changed course quickly. The powerboat missed the stern by a few inches and threw a heavy spray of water over the boys. Its wake rocked the sailboat violently.
“Hold fast!” Frank cried out. “Stay in the center, fellows, or we'll capsize!”
“Look!” Joe yelled. “They've turned and they're coming at us again!”
As the powerboat sped perilously close, more water foamed over the gunwales.