"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?"
Frank sat straight up in bed. "I'm sorry, he isn't here," he replied. "I'll call some of our friends and see what I can find out."
Biff's mother gratefully accepted the offer. "Oh, thank you. I'm so worried about him."
As Frank put down the phone, Joe mumbled sleepily, "What's the matter?"
"Matter? It looks as if plenty's the matter. Wake up! Chet and Biff are missing!"
CHAPTER VI
A Perilous Slide
STARTLED by the news, Joe sat bolt upright in bed. "Chet and Biff gone?"
"They vanished after the party."
"Who was that on the telephone?" suddenly asked a deep voice. In the doorway stood Fenton Hardy in a robe.
Quickly Frank told his father and Joe about the calls from Mrs. Morton and Mrs. Hooper. Mr.
Hardy promptly dialed police headquarters, and identified himself to the desk sergeant.
"Have any accidents been reported since midnight?" he inquired. As he listened, the lines of his forehead relaxed.
"None," he reported to Frank and Joe. Then the detective explained the situation to the officer, who promised that the police would look for Chet and Biff.
After putting down the phone, Mr. Hardy asked his sons, "Is there any place the boys are likely to have gone?"
"They were planning to go camping early this morning," Joe recollected, "stopping at different islands along the coast. Maybe they decided to go tonight instead."
"I doubt it-in this fog," Frank objected. "And not without telling anyone." Nevertheless, he dialed the Hooper home to make sure.
"Oh, no," Biff's mother replied to Frank's question. "Mr. Hooper carries the boathouse key with him. If Biff and Chet had wanted to leave earlier, they would have had to get it from him."
Frank tried not to show his mounting alarm. Hoping he sounded cheerful, he said, "We'll keep looking for the boys." After saying good-by, he turned to Joe and his father. "This is serious. I hate to disturb Callie, but I'll have to now." He dialed her number. Callie herself answered sleepily.
"Sorry to bother you so late," Frank said. "But will you do me a favor? Peek out the window and see if Chet's jalopy is there. It was parked under the street light."
After a short pause he turned to Joe and his father. "It's still there! . . . Callie, when did Biff and Chet leave?" He listened a moment. "Thanks. We can't locate them. . . . Nothing wrong for sure yet. We'll call you tomorrow."
Frank hung up and said worriedly, "They left the party ten minutes after we did."
Joe snapped his fingers. "I'll bet they couldn't get the jalopy started. They're probably spending the night with one of the fellows who lives on Callie's street."
Frank looked relieved. "Let's go over and check the jalopy." The boys began dressing.
"Have you a key to the car?" Mr. Hardy asked.
"Chet gave us one," Frank explained.
Fifteen minutes later the boys drove up quietly in their father's sedan and parked behind the
yellow jalopy. Quickly Frank slipped into the driver's seat, and a moment later the Queen
coughed and rattled into life. Abruptly he cut the motor and the two brothers looked at each
other soberly.
"I was wrong," Joe said. "They didn't have car trouble. What did happen?"
Frank shook his head grimly. By the light of the street lamp the boys examined the jalopy, the curb and road around it, but found no clues. Using their flashlights, they checked the Shaws'
yard and porch.
"Nothing here," Frank said finally.
The porch lights blinked on and Callie appeared in the doorway. "Frank-Joe, what are you
doing?" she asked.
"Looking for clues," Joe replied. "But we haven't found any yet."
"Chet and Biff had their costumes on when they left, and carried the masks," Callie said. "They looked so conspicuous, they should be easy to locate."
"We'll keep trying," Frank promised.
He used the Shaw phone and called each boy who had been at the party. Chet and Biff were
not with any of them, nor had Tony or Jerry heard from them.
Finally the Hardys headed for home. They gave their father the discouraging report and
reluctantly went back to bed.
After a few hours of uneasy sleep, Frank and Joe awakened to find bright sunlight filling the
room.
Hurriedly they dressed and dashed downstairs. Their father was already at the breakfast table.
"Any news of Chet and Biff?" Frank asked.