The Secret of the Old Mill (6 page)

“Hey! This looks like a tunnel!”

Excitedly Joe poked his flashlight into the opening. In its beam they could see that the hole appeared to extend into the side of the bank.

“Let's see where the tunnel goes!” Joe urged.

“Okay,” Frank agreed eagerly. “We'll have to move more of these rocks before we can climb through. I wonder who put them here and why.”

Rapidly the boys pushed rocks aside until the narrow tunnel entrance was completely exposed. Joe crawled in first, then Frank.

Chet tried to squeeze his bulky form through the space but quickly backed out. “It's too tight for me,” he groaned. “I'll stay here and collect more specimens. Anyhow, I'll bet some animal made the tunnel and it doesn't lead anywhere.”

“I'm sure no animal did this,” Joe called back, aiming his flashlight at the earthen walls of the tunnel. “Look how hard-packed the sides are—as if dug out by a shovel.”

Frank was of the same opinion. He pointed to rough-hewn wooden stakes placed at intervals along the sides and across the ceiling. “I wonder who put those supports here—and when.”

The Hardys crawled ahead carefully. There was just room in the passageway for a normal-sized person to get through.

Presently Joe called back to his brother, “Look ahead! I can see a sharp bend to the right. Let's keep going.”

Frank was about to reply when the brothers were startled by a girl's scream from outside.

“That's Callie!” Frank exclaimed. “Something's wrong!”

CHAPTER VII

FRANK and Joe scrambled through the tunnel and out of the cave. They found Chet and the girls staring at an arrow embedded in the sandy beach.

“It—it almost hit us,” Iola quavered. Callie, who was white-faced with fear, nodded.

Joe was furious. “Whoever shot it shouldn't be allowed to use such a dangerous weapon!” he burst out. “That's a hunting arrow—it could have caused serious injury.”

Chet gulped. “M-maybe the Indians haven't left here, after all,” he said, trying to hide his nervousness.

Joe turned to dash off into the woods to search for the bowman.

“Wait!” Frank called. He had pulled the arrow from the sand. “This was done deliberately,” he announced grimly, holding the arrow up for all of them to see. Attached to the shaft just below the feathers was a tiny piece of paper. It had been fastened on with adhesive tape.

Frank unrolled the paper and read the printed message aloud:
“ ‘Danger. Hardys beware.' ”

Chet and the girls shuddered and looked around fearfully, as though they expected to see the bowman behind them.

“You boys
are
involved in a new mystery!” Callie exclaimed. “Your own or your father's?”

Frank and Joe exchanged glances. It certainly seemed as though they were involved, but they had no way of knowing
which
case. Did it involve the counterfeit money? Or was it the case their father could not divulge?

“A warning did come to Dad,” Frank admitted. “This one obviously was meant for Joe and me. Whoever shot the arrow trailed us here.”

Joe frowned. “I wonder if the same person sent both warnings.”

“I still think Ken Blake could give us a clue,” Frank said. “But we must remember that anybody could have taken the bike from the storage place under the mill.”

Frank pocketed the latest warning, then the five searched quickly for any lead to the bowman. They found none. When the group returned to the beach, Joe looked at the sky. “We're in for a storm—and not one of us has a raincoat.”

The bright summer sun had disappeared behind towering banks of cumulus clouds. There were rumbles of heavy thunder, followed by vivid flashes of lightning. The air had become humid and oppressive.

“Let's get out of here!” Chet urged. “This isn't a picnic any more!”

The young people hastened through the woods and up the road to Chet's jalopy. As they drove off, rain began coming down in torrents. The sky grew blacker.

Callie shivered. “It seems so sinister—after that awful arrow.”

Chet dropped his sister off at the Morton farm and at the same time picked up his new microscope. He begged to try out the instrument on both warning notes and the Hardys smilingly agreed, although they had an up-to-date model of their own.

By the time they had said good-by to Callie at her house, and Chet had driven the Queen into the Hardys' driveway, the storm had ended. The sun shone brightly again.

Immediately the three boys went to the laboratory over the garage. Here Frank carefully dusted the arrow and the second warning note for prints. He blew the powder away, and Joe and Chet looked over his shoulder as he peered through the magnifying glass.

“Nothing. Same as the warning to Dad. The person no doubt wore gloves.”

“Now to compare this paper to the first note,” Joe said.

“Right,” his brother agreed. “You have the combination to the cabinet in Dad's study. Chet and I will rig up his microscope while you get the note from the file.”

Frank and Chet focused and adjusted the microscope, making sure it was level on the table. They plugged in the illuminator and checked to see that it did not provide too dazzling a reflection. When Joe returned, Chet took the two pieces of paper and fitted them side by side under the clips on the base.

“Okay. Want to take a look, fellows?” Frank, then Joe, studied both papers. “The quality and texture are definitely the same,” Frank observed.

Next, he lifted the second note from under the clips and slowly moved the paper back and forth under the lenses.

“A watermark!” he exclaimed, stepping back so the others could look at the small, faint imprint.

“Sure is!” said Joe. “A five-pointed star. This could be a valuable clue! We can try to track down exactly where this paper came from.”

“And also the arrow,” said Chet. “I'll make the rounds of sport stores in town.”

“Swell, Chet. Thanks,” Frank said.

After their friend had left, the Hardys consulted the classified directory for paper manufacturers.

They made several calls without any luck. Finally they learned that the Quality Paper Company in Bridgeport manufactured paper bearing the five-pointed star watermark. The brothers wanted to go at once to get more information, but realized this errand would have to wait.

“Dad will be home soon,” Frank reminded his brother. “We don't want to miss our surprise!”

“Right. And I'd like to tell him about the warning on the arrow.”

When Chet returned from a round of the sports shops, he was glum. “I wasn't much help,” he said. “The arrow isn't new, and all the stores I checked told me it was a standard model that could be purchased at any sports shop in the country.”

“Never mind, Chet,” said Frank. “At least giving your microscope a trial run helped us to spot the watermark on the second warning note. We've located a company that manufactures paper with the star watermark.”

Chet's face brightened. “Let me know if you find out anything else,” he said, packing up his microscope. “I guess I'll take off—and do some nature study for a change.”

After he had driven off, Frank and Joe walked to the house. Their minds once more turned to the surprise Mr. Hardy had for them.

“Wouldn't it be terrific if—” Joe said to Frank excitedly. “Do you think it
is?”

“I'm just hoping.” Frank grinned.

Just then a newsboy delivered the evening newspaper. The brothers entered the house and went into the living room. Frank scanned the front page and pointed out an item about new trouble in an Indiana electronics plant.

“That's where an explosion took place a couple of months ago,” Joe remarked. “Sabotage, the investigators decided.”

“And before that,” Frank added, “the same thing happened at a rocket research lab in California. Another unsolved case.”

“Seems almost like a chain reaction,” Frank remarked.

Any mystery appealed to the boys, but they did not have much chance to discuss this one. The telephone rang. Aunt Gertrude, after taking the call, burst into the living room. From the look on her face Frank and Joe could tell she was indignant, and at the same time, frightened.

“What's the matter, Aunty?” Joe asked.

“More threats—that's all!” she cried out. “This time by telephone. A man's voice—he sounded sinister—horrible!”

Mrs. Hardy came into the living room at that moment. “What did he say, Gertrude?” she asked.

Aunt Gertrude took a deep breath in an effort to calm down.
“ ‘Hardy and his sons are playing with fire,'
the man said.
‘They'll get burned if they don't lay off this case.”'
Miss Hardy sniffed. “I don't know what case he meant. What kind of danger
are
you boys mixed up in now?”

Frank and Joe smiled wryly. “Aunt Gertrude,” Frank replied, “we really don't know. But please try not to worry,” he begged her and his mother. “You know that Dad and the two of us will be careful.”

When Mr. Hardy came home a little later, his family told him about the threatening telephone call. The boys, however, did not mention the arrow warning in the presence of their mother and Aunt Gertrude. They knew it would only add to their concern.

Mr. Hardy was as puzzled as his sons. “It's a funny thing,” he said. “At this point it's impossible to tell which ‘case' the person is referring to. If I knew, it might shed light on either one.”

The detective grinned and changed the subject. “Right now, I want you all to come for a drive and have a look at the boys' surprise.”

“Swell!” Frank and Joe exclaimed in unison.

While Aunt Gertrude and Mrs. Hardy were getting ready, Frank and Joe went out to the car with their father. Quickly the boys related their afternoon's experience, concluding with the arrow incident.

The detective looked grim. “Whoever is responsible for these warnings is certainly keeping close tabs on us.”

Mr. Hardy and his sons speculated for a few minutes on the fact that the pedal found in front of the house apparently had belonged to Ken's bike.

“I think Joe and I should go back tonight to the place where we had the picnic,” Frank told his father. “In the darkness we'll have a better chance to sleuth without being seen. And there might be some clue we missed this afternoon.”

“I suppose you're right,” agreed his father. “But be cautious.”

As Aunt Gertrude and Mrs. Hardy came out of the house, conversation about the mystery ceased. Everyone climbed into the sedan and Mr. Hardy drove off. Frank and Joe, seated alongside him, were in a state of rising suspense. Was the surprise the one thing they wanted most of all?

CHAPTER VIII

A FEW minutes later Mr. Hardy was driving along the Bayport waterfront.

“Is the surprise here, Dad?” Joe asked excitedly.

“That's right.”

Mr. Hardy drove to a boathouse at the far end of the dock area and parked. He then invited the others to follow him. He walked to the door of a boathouse and unfastened the padlock.

Frank and Joe held their breaths as Mr. Hardy swung back the door. For a moment they stared inside, speechless with delight. Finally Joe burst out, “Exactly what we had hoped for, Dad!” and put an arm affectionately around his father.

“What a beauty!” Frank exclaimed and wrung Mr. Hardy's hand.

Rocking between the piles lay a sleek, completely equipped motorboat. It nudged gently against clean white fenders as the waves from the bay worked their way under the boathouse door.

The boys' mother exclaimed in delight, and even Aunt Gertrude was duly impressed by the handsome craft.

“This is the same model we saw at the boat show,” Joe said admiringly. “I never thought we'd own one.”

“She even has the name we picked out,” Frank observed excitedly. “The
Sleuth!”

Shiny brass letters were fitted on the bow of the boat, with the port of registry, Bayport, underneath them.

Mr. Hardy and his wife beamed as their sons walked up and down, praising every detail of the graceful new craft. It could seat six people comfortably. The polished fore and aft decks carried gleaming anchor fittings, and the rubbing strakes were painted white. The Sleuth seemed to be waiting to be taken for a run!

“May we try her out now, Dad?” Joe asked.

“Of course. She's fueled up.”

Aunt Gertrude shook her head. “The
Sleuth's
an attractive boat, all right. But don't you two start doing any crazy stunts in it,” she cautioned her nephews. “And be back for supper.”

When the adults had left, Frank and Joe climbed aboard and soon had the
Sleuth
gliding into the bay. The boys had no difficulty operating the motorboat. They had gained experience running their friend Tony Prito's boat, the
Napoli,
which had similar controls.

Taking turns at the wheel, the brothers ran the boat up and down the bay. “Terrific!” Joe shouted.

Frank grinned. “Am I glad we stuck to our agreement with Dad, and saved up to help buy this!”

For some time the boys had been putting money toward a boat of their own into a special bank account. Mr. Hardy had promised that when the account reached a certain sum, he would make up the necessary balance.

Now, as the
Sleuth
knifed through the water, Frank and Joe admired the way the stern sat down in the water when the boat gathered speed. Joe was impressed with the turning circle and the fact that no matter how sharp the twist, none of the spume sprayed into the cockpit.