“That is very generous, sir,” Jupiter acknowledged.

“Oh, no!” Bob cried. “Look, the door!”

On the drawn blind of the rear door they all saw a massive shadow with wild hair, beard, and enormous shoulder muscles. “That’s the shadow!” Pete hissed.

Mr. Carson walked quickly to the door, opened it, and then turned to the boys smiling. A man entered, and the boys gaped at him. He was only normally tall, but his bare shoulders bulged with muscles. He wore only black-and-gold tights, which clung to his powerful legs like skin, and tight, gleaming leather boots. His black hair and beard stood out wild and thick.

“This,” Mr. Carson said, smiling, “is Khan, our strong man. One of your mysteries is explained, boys. Khan, like all of us, has more than one job. He’s in charge of our security. I’d guess he saw you slipping round and decided to check on you.”

“That is correct,” Khan said in a deep, serious voice.

Mr. Carson nodded. “There you are then, boys. Now I have business with Khan, and Andy must go back to his job. Go and have fun. Remember, it’s all free.”

“Thank you, sir,” Jupiter said quietly. He motioned to Bob and Pete. Outside the truck, Jupiter walked ahead until they were behind a trailer, out of sight of the truck. Then he suddenly stopped, ducked down, and peered back.

“’What are you doing, Jupe?” Bob asked.

“I’m sure something is wrong in this carnival, Records” the First Investigator said. “That Khan has something on his mind. He didn’t look much like a guard when he was listening to us. And I’m sure Andy would have told us something if his father hadn’t stopped him. Let’s get closer to that window and listen.”

“Wait!” Pete said quickly.

Andy Carson came out of the truck and hurried away towards his shooting gallery. The boys slipped up to the window, Khan’s deep voice was saying.

“… now Rajah escapes. What next, Carson? Maybe we won’t be paid at all.”

“You’ll all be paid next week. Khan,” Mr. Carson said.

Khan said, “You know how superstitious carnival people are. The show is unlucky. There will be more trouble.”

“Now, Khan, listen to me. You — ” There was a step inside, and the window banged shut above the boys’ heads. They heard no more and hurried away.

“Gosh, there is trouble,” Pete exclaimed, “but what can we do if Mr. Carson won’t even talk about it?”

Jupiter was thoughtful. “He won’t let Andy talk, either, but we have passes, and we can watch. Tomorrow, Bob can check the newspapers at the library for any stories of trouble at the carnival in other towns. Tomorrow, we’ll meet and see what we can decide.”

“What are you going to do, First?” Bob asked.

“I think,” Jupiter said ominously, “I shall spend the rest of the night in search of the necessary knowledge.”

Pete slept badly that night, trying to think of ways to make Mr. Carson let the boys investigate. By morning he still had no ideas and was eager to find out if the other Investigators had thought of something. He hurried down to breakfast and found his father was up ahead of him.

“Gosh, you’re up early, Dad,” Pete said.

“A hurry call from Alfred Hitchcock,” Mr. Crenshaw explained, “Some special work on our new picture. Unfortunately, Pete, I promised your mother I’d clean out the basement today. I’m afraid you’re elected to do it for me.”

Pete groaned inwardly and said, “Sure, Dad. I’ll do it.”

That was why Pete didn’t pedal his bike up to the Jones Salvage Yard until after lunch. In the yard he made his way to a long section of corrugated pipe that seemed to vanish into the mounds of junk. This was Tunnel Two, the main entrance to Headquarters. Pete crawled into the pipe and emerged up through the trap door into the trailer. Jupiter was there.

“Have you thought of a way to get Mr. Carson to let us help?” the First Investigator asked promptly.

“No,” Pete sighed. “I can’t think of anything.”

“Neither can I,” Jupiter admitted glumly. “I guess we don’t have a chance unless Bob finds something to help us at the library. I’ve been waiting for him.” Jupiter was standing at the See-All, and now he peered into the eyepiece again. The See-All was a crude but efficient periscope Jupiter had built to remedy the one disadvantage of Headquarters — they couldn’t see out. The See-All stuck up above the junk that hid the trailer, looking like a piece of ordinary pipe, and the boys could see most of the salvage yard.

“There he is now!” Jupiter cried.

Moments later, Bob came up through the trap door waving a notebook and looking excited.

“You found troubles at the carnival?” Pete exclaimed.

Bob beamed. “It took all morning, but I got it! The carnival isn’t very important, so I had to read most of the small-town newspapers.”

“What did you find. Records?” Jupiter asked impatiently.

Bob opened his notebook. “Three weeks ago the carnival lost its pony ride in Ventura. Three of the ponies died of food poisoning. Then, three days ago there was a fire when they were just north in San Mateo. Three tents were burned; the fire eater’s tent, the lion tent and part of the shooting gallery. They were lucky to stop it.”

“The lion tent?” Pete exclaimed. “That makes trouble there twice.”

“It could be coincidence,” Jupiter said. “We must never jump to conclusions. But it would be interesting to know if the pony ride was also located in the same carnival area.”

“The papers didn’t say, First,” Bob said.

“No,” Jupiter said thoughtfully. “Both so-called accidents could have been much worse. The carnival was lucky, unless — ” Jupiter did not finish that thought. “I assumed that those two other accidents were all you found. Records?”

“How did you know that, Jupe?” Bob asked, puzzled.

“Last night we heard Khan mention superstition,” Jupiter reminded them. “After I got home I talked to Uncle Titus and read some of his books — you remember Uncle Titus worked in a circus. One of the oldest carnival superstitions is that accidents happen in threes. So Rajah’s escape was the third!”

“Gosh, do they still believe that?” Pete asked.

“Carnival people tend to live apart, Second, and hold to old beliefs,” Jupiter explained. “But I did more than read carnival history last night. Uncle Titus told me of a book that lists all circus and carnival performers. I called the reference room of the Los Angeles library this morning. There is no listing for a strong man named Khan!”

“Khan’s a fake?” Pete exclaimed.

“It could be he hasn’t performed recently,” Jupiter admitted. “Or he could be from out of the country. But there is something suspicious about Khan.” His eyes gleamed. “And I’ve got an idea of how to get us involved with the carnival. We won’t convince Mr. Carson right away, but I think if we get Andy here we can convince him by following my plan.”

“What plan is that, Jupe?” Pete asked.

Jupiter began to explain his plan, and after a few minutes both of the other boys were grinning and nodding.

A short while later Pete was again watching the salvage yard through the See-All. “Here he comes, fellows!”

When the blond carnival boy came up to the workshop outside Headquarters, Pete was waiting for him.

“What’s up, Pete?” Andy asked.

“We thought you might like to see our secret Headquarters, and how we work,” Pete said. “Come on.”

He led the carnival boy into Tunnel Two and up through the trap door into the trailer.

“Jiminy! What a neat place!” Andy cried.

He stared wide-eyed at the microscope, telephone, periscope, walkie-talkies on the wall, filing cabinets, metal detector, shelves of books and trophies, and all the other equipment the boys had arranged so that Andy couldn’t miss it. He looked at Bob and Jupiter, who seemed to be hard at work. Neither of them even glanced up. Jupiter was peering through magnifying goggles at a lock and a book. Bob was studying something under a lighted glass screen.