them. But now all three boys heard the sound of a boat engine.
'You were right,' Joe whispered. 'I think it is the Sleuth. Listen!'
The high-pitched whine drew slowly closer, then gradually receded. Soon it approached again.
'She's going in circles!' Joe chortled gleefully. 'Head toward her, Tony.'
'Sure. But which way?'
'To the right,' Joe said promptly.
'Straight ahead!' Frank countered.
Tony started his engine and headed midway between the two directions. He drove steadily
forward until Joe signaled to cut it again.
The other craft was very near them and over the motor's purr they could hear angry voices.
'It won't work!' one cried out. 'Try it yourself!' Another shouted, 'Move over, then!'
Frank, Joe, and Tony listened, grinning, while the men argued about the disabled boat.
Suddenly the Sleuth's motor was silent.
'They're drifting away,' Frank said quietly.
Although Tony followed in the direction he thought the other boat was taking, the voices grew
faint.
Desperately Tony opened his throttle wide, then shut off the motor again to listen. The voices had ceased.
'The men must have heard us,' Joe whispered. 'They probably know they're being chased.'
For a time the eerie pursuit continued, but at last Frank said, 'It's no use. They could have drifted a mile away by now.'
'Or they could be five feet from us,' Joe whispered. 'We'll never find them in this fog.'
'Besides, we're low on gas,' Tony added, and turned the Napoli toward Bayport.
'Joe and I will come to the party later,' Frank told Tony. 'I think Dad would like to hear our account of the bank robbery.'
After dropping Frank and Joe at the Coast Guard pier, Tony returned his boat to its mooring and went back to Callie's house. Meanwhile, the brothers, dejected, cycled home. Opening the front door, they found their father in the hall taking his hat from the rack. Mr. Hardy stopped short.
'Tell me what you know about the bank holdup,' he said crisply. His sons stared in surprise.
Then Frank grinned. 'I guess Chief Collig told you about us, didn't he?'
'Yes,' replied Mr. Hardy. 'He just phoned to ask my help. I'm on my way downtown. Brief me quickly.'
The detective listened with keen interest while his sons poured out the story of the robbery and the missing Sleuth.
'One thing is odd,' Frank added when they had finished. 'The tellers swear the thieves were all the same size and build.'
Fenton Hardy smiled. 'That's not so strange.'
'You mean the men were identical in size?' Frank asked.
'Not at all,' their father answered. 'But a large mask will make a person's body seem smaller. A tiny face mask can make him look bigger.'
'So the robbers used the masks to disguise their builds as well as their faces,' said Frank.
'Exactly,' his father answered. 'It sounds like a very clever gang.'
At that moment Aunt Gertrude came into the living room. 'Fenton,' she said, her voice sharp with disapproval, 'there was a special news bulletin on the radio just now saying that you've taken on the Bayport bank robbery case.'
'So I have,' Mr. Hardy replied mildly, though the boys knew he was an expert at this. 'At least to help the local authorities,' he added.
'But why do they announce it?' his sister asked tartly. 'The bank robbers may hear it, and who knows what those dangerous men might do to make you drop the easel'
'Don't worry, Gertrude,' Mr. Hardy replied kindly. 'I'll be careful. Thanks for the information, boys,' he added, and hurried off.
Aunt Gertrude eyed Frank and Joe suspiciously. 'What are you two going to do now?' she demanded.
'Nothing dangerous, Auntie,' Joe assured her. 'We're just going to Callie's party.' Satisfied, Miss Hardy watched the boys depart.
'Aunt Gertrude's right, you know,' Frank remarked as they walked to their motorcycles in the drive. 'It's too bad about that radio bulletin. Dad is safer if he works under cover.'
A short ride brought Frank and Joe to the Shaw house. They parked their motorcycles beside
the garage and quickly put on their costumes. Carrying the two containers of ice cream, the
gorilla and the magician walked to the door, where they were admitted by a smiling Mrs. Shaw.
'Hello, boys. Come right in! I'll put the ice cream away.'
When the Hardys entered the big living room they were hailed by a camel with four human
legs, Spaceman Prito, and many other fantastic figures.
Pretty, brown-haired Callie was dressed as a fairy princess, and slim, vivacious Iola as a page boy. The two girls hurried forward to greet the late arrivals.
'Tony told us about the robbers and the chase,' Callie said.
'We're glad you got here!' Iola added warmly.
A fierce pirate strode up to them. 'I'm Black-beard Biff Hooper,' he announced. 'How'd you like to walk the plank?'
Before Frank could answer, there was a ferocious roar behind him and a hand clamped down
on his shoulder. He whirled to find himself face to face with another gorilla!
'Told you I'd surprise you!' came Chet Morton's voice. 'Come on, Gargantua! Let's dance!'
The two hairy creatures joined hands and waltzed around the room to the music of the record
player.
They pirouetted, leaped in the air, and did somersaults. The other guests watched, shrieking
with laughter. Panting, Chet yanked off his tight-fitting gorilla face.
'Oops!' he exclaimed ruefully. 'I tore it.'
Frank examined the rubber mask. 'Too bad,' he said with a grin. 'You'll have to wear your own face from now on.'
Later, as the guests ate, they listened, fascinated, to the Hardys' account of their adventure.
Finally, about midnight, everyone began to leave.
As Frank and Joe were saying good night to the girls, Chet came over to them. 'Biff, Tony, Jerry, and I have decided to go camping tomorrow. We're using Mr. Hooper's boat. Sorry you fellows
can't come.'
'We'll make it next time,' Joe promised.
Iola said to Chet, 'You can go on home and drop Biff at his house. I'm staying overnight here.'
'Okay, Sis.'
Frank and Joe departed, and soon after returning home, they were sound asleep. Two hours
later the ringing of the telephone jarred the silence of the Hardy home. Frank awoke and picked up the extension phone.
'Hello.'
'Frank?' The speaker was Mrs. Morton. 'Is Chet there? He hasn't come home yet!'
'No, he isn't here,' Frank answered. 'He probably went to Biff's.'
'I'll try the Hoopers,' Mrs. Morton said. 'Sorry to have awakened you.'
As Frank replaced the telephone, he glanced at his wrist watch. It was two o'clock.
'Funny Chet didn't phone his folks,' he thought.
A second later the phone jangled again and he picked it up. 'Frank Hardy speaking.'
'This is Mrs. Hooper,' said a worried voice. 'Is Biff with you?'
