about you boys coming home last night half dead?'
The boys explained, omitting none of the details. 'We didn't want to alarm Mother and Aunt Gertrude,'
Frank said, 'so we didn't tell them about the attack.'
Mr. Hardy looked grim and warned his sons gravely to be extra cautious.
'There's one bright spot,' he added. 'The print you found on that finger guard. It could be a big break.'
During lunch the detective was unusually preoccupied. The boys tried to draw him out by
questions and deductions about the counterfeiting case. He would say very little, however, and seemed to be concentrating on a knotty problem.
A little later the boys rode their motorcycles straight to the boathouse and parked at the street end of the jetty. 'Chet ought to show up soon,' Joe remarked.
As the brothers walked toward the boathouse Frank commented on his father's preoccupation
during luncheon.
'I have a hunch Dad's assignment is even tougher than usual,' he confided. 'I wish we could help him on it.'
Frank seemed to be only half listening and nodded absently.
'What's the matter with you?' Joe laughed. 'I'm talking to myself!'
Suddenly Frank stopped. He grasped his brother's arm firmly.
'Joe!' he said. 'We may have found a clue in Bridgeport this morning, and didn't realize it!'
CHAPTER X
The Sign of the Arrow
'WHAT clue do you mean, Frank?' Joe demanded eagerly.
'Elekton's name was on that list Mr. Evans showed us this morning.'
'Yes, I know. But Dad didn't seem excited over that.'
'Well, I am,' Frank said. 'Put two and two together. Every time we've been near the Elekton area, something has happened. First, the warning on the arrow, then the attack last night.'
'Of course!' Joe said. 'I get you! Someone who has access to the company's paper supply could have sent the warnings, and knocked us out. But who? An employee of Elekton?'
'That's the mystery,' said Frank. 'Is the person trying to get at Dad through us? And which of the cases is this mysterious person connected with '-the counterfeit case or Dad's secret one?'
'Then there's the bike,' Joe recalled. 'Someone from the company easily could have taken it from the storage area under the mill at night when the guard and maintenance man were
inside the gatehouse.'
'Joe,' said Frank slowly, 'we're theorizing on the case having a connection with Elekton. Do you think Dad is, too, even though he didn't tell us? The Elekton name may have been the clue he
found at Quality Paper!'
Joe snapped his fingers. 'My guess is that Dad is doing some detective work for Elekton! That would explain why he can't say anything. Elekton is doing top-secret space missile work.'
'It's possible,' Frank speculated, 'that Elekton retained Dad because of the chain of sabotage acts in plants handling similar jobs for the government.'
'Sounds logical,' Joe agreed. 'I guess Dad's main assignment would be to ward off sabotage at Elekton.
No wonder he is so anxious to find out who sent the warnings.'
Just then Chet arrived in the Queen and leaped out.
'I have a job!' he announced to Frank and Joe. Then he looked a bit sheepish. 'It's-er-in the cafeteria, serving behind the food counter. The cafeteria is run on a concession basis, and the people working there aren't as carefully screened as the plant employees.'
Joe grinned. 'It's not very scientific, but think of the food! You'll be able to eat anything you want.'
Chet sighed, and did not respond with one of his usual humorous comebacks. A worried
expression spread over his face. He shifted from one foot to the other.
'What's on your mind?' Joe prodded. 'Not nervous about the job, are you?'
Chet shook his head. He dug into his pocket and pulled out a piece of white paper. 'I am
nervous about this-another warning note! It was on the seat of my car when I came out after
the job interview.' He handed the note to Frank.
Unfolding it, Frank read aloud, ' 'You and your pals watch out!' ' There was no signature on the boldly printed note, but at the bottom was the crude drawing of an arrow.
Chet gulped. 'Must be that arrow shooter. He's keeping tabs on all of us!' he said.
Frank and Joe studied the note intently for a minute, then Frank asked Chet, 'Where did you park?'
'Near the front entrance. The guard at the mill told me to go in that way to reach the personnel office.'
Chet smiled faintly. 'Boy, was he surprised when I told him I had an appointment.'
The Hardys were more convinced than ever that their unknown enemy must somehow be
linked with the Elekton company. 'We'll compare this note with the others,' Frank said. 'But first, Chet, we'll show you something to cheer you up.'
The brothers led their friend into the boathouse. 'Feast your eyes!' Joe grinned. 'This is our surprise.'
Chet gasped when he saw the Sleuth. 'Wow! She's really yours?'
'You bet! How about a ride?'
Eagerly Chet accepted. As the Hardys refueled from the boathouse tank, they told Chet about
the adventure they had had the previous night.
'You suspect there's a connection between somebody at Elekton and the counterfeiting?' Chet guessed.
'That's right,' Frank replied.
He then told Chet about the Pritos having received a counterfeit bill, 'We think,' said Joe, 'the boy in the panel truck who gave Mike the counterfeit twenty might have been Ken Blake,'
'Ken Blake again,' Chet commented. 'Funny how he keeps turning up.'
The Hardys agreed. As Frank steered the Sleuth into the bay, Joe suggested, 'Let's run up Willow River to the mill. That'll give you a good chance to see how the boat rides, Chet, and
also we can stop to question the guard and maintenance man, and Ken Blake. They might have
seen some suspicious people in the area.'
'I should've known this would turn into a sleuthing trip.' Chet sighed. 'Oh, well, I'm with you if we can learn anything about the counterfeiters.'
When Frank had the Sleuth well away from shore and out of the path of other craft on the bay,
he pushed the throttle for more speed and steered the boat toward the mouth of the river.
The Sleuth responded like a thoroughbred. The stern sat back in the water and in a second it
was planing wide open across the bay.
'How do you like this?' Frank called from the cockpit.
'Terrific!' Chet yelled back enthusiastically.
Frank now swung the wheel back and forth to show his friend how stable the boat was. Then he
said, 'Joe, take the wheel and show Chet your stuff!'
The brothers changed places and Joe made a wide circle to port, with the Sleuth heeling
beautifully. Then he headed for the river's narrow mouth.
'Better slow down!' Frank warned him.
Obediently Joe began to ease the throttle. The Sleuth did not respond! And there was no
lessening of the roar of the engine.
Quickly Joe turned the throttle all the way back. Still there was no decrease in speed.
'Something's wrong!' he shouted. 'I can't slow her down!'
CHAPTER XI
Sinister Tactics
'WHAT do you mean you can't slow down?' Chet yelled. 'Turn off the engine!'
'Joe can't,' Frank said grimly. 'He has the throttle to off position and we're still traveling at full speed.'
