The boys moved a piece of old iron grating hidden by the printing press, uncovering the mouth of a large section of corrugated pipe. They crawled into it, replaced the grating, then went forward on hands and knees about forty feet. The pipe went underground some of the way, then ran between some nondescript iron beams. It opened at the other end directly under the mobile trailer which the boys had converted into Headquarters. When Jupiter’s uncle, Titus Jones, found he couldn’t sell the old trailer, he had given Jupiter and his friends permission to use it.

The boys pushed a trap-door upwards and scrambled through. Then they were inside a tiny office fitted with a desk, a few chairs, a typewriter, filing cabinet and a telephone. Jupiter had connected a microphone and radio loudspeaker to the telephone, which permitted the boys to listen to any phone conversation together. The remainder of the trailer consisted of a tiny darkroom, a miniature lab and a washroom.

Because the trailer was surrounded by piles of junk outside, it was dark inside. Pete switched on the light over the desk.

At that moment the telephone rang.

The boys looked at one another. Hardly anyone ever phoned them.

After the second ring, Jupiter reached for it, switching on the little radio loudspeaker.

“Jupiter Jones?” asked a woman’s voice. “Alfred Hitchcock is calling.”

“Wow!” Bob yelled. “Maybe he has another good case for us!” Ever since Mr. Hitchcock, the famous film director, had learned of The Three Investigators, he had put them on several cases.

“Hello, young Jones!” It was Mr. Hitchcock speaking. “Are you and your friends busy on a case at the moment?”

“No, sir,” Jupiter said. “But according to the law of averages we should find something interesting soon.”

Mr. Hitchcock chuckled,

“Law of averages, indeed!” he said. “If you’re not busy, I have something for you. An old film director friend of mine can use some help.”

“We’d be glad to try, Mr. Hitchcock,” Jupiter said. “What is your friend’s problem?”

Mr. Hitchcock hesitated, as if he were trying to sum up a difficult situation in a few words.

“It appears to be dog trouble,” he said finally. “That is to say, he told me on the telephone a little while ago that his dog is missing.”

Jupiter’s eyes brightened. “Would your friend happen be a resident of the town of Seaside, Mr. Hitchcock?” asked.

There was a brief silence.

When Mr. Hitchcock came on again, he sounded thunderstruck. “He does live in Seaside, for a fact, young Jones. Now how on earth did you deduce that?”

“Merely putting a few odd occurrences together,” Jupiter said.

“Remarkable,” Mr. Hitchcock was saying. “Quite remarkable, really. I’m pleased that you are still alert and not permitting your organization to become stagnant with conceit and boredom.”

Jupiter grinned. “Not a chance, Mr. Hitchcock. But you said that your friend ‘appears’ to be having dog trouble. You put stress on the word ‘appears,’ sir. Was that your intention?”

“As a matter of fact,” Mr. Hitchcock said, “you have guessed quite accurately what I was intending to communicate. I don’t believe this is an ordinary case, at all. When you think of it, no case that involves a dragon can be considered ordinary. Wouldn’t you agree?”

Jupiter cleared his throat, “A dragon?”

“Yes, my boy. My friend’s house overlooks the ocean, and there are caves running beneath it. The night that his dog disappeared, my friend insists he saw a rather large dragon emerge from the ocean and enter one of the caves underneath his dwelling.”

There was a stunned silence.

“Well, what do you say, my boy? Are you and your companions willing to try to unravel this mystery?”

Jupiter was so excited, he started to stutter. “J-j-just give me your friend’s name and address, sir!” he said. “This sounds as if it could be our most exciting case!”

He wrote down the information Mr. Hitchcock gave, promised to report all progress, and hung up. He looked at Pete and Bob triumphantly.

“Anything about a dragon living in our times should be investigated. Don’t you agree?”

Bob nodded. Pete shrugged.

“You seem to have some reservations, Pete,” Jupiter said.

“You made only one mistake,” Pete said, “You told Mr. Hitchcock it could be our most exciting case.”

“Well, yes, I did,” Jupiter replied. “Don’t you agree?”

“Not entirely,” Pete said.

“What would you have said, then?”

“As long as there’s a dragon in it,” Pete said, “I would have said — this could be our last case!”

The town of seaside, where Mr. Hitchcock’s film director friend lived, was about twenty miles away along the Pacific Coast Highway. Hans, one of the two Bavarian yard helpers, had a collection and delivery to make in the area after lunch. Jupiter got permission from his Aunt Mathilda to be taken along with his friends in the small junk yard truck.

Jupiter’s aunt fed them all, and then they hurried out and piled into the front with Hans. Jupiter gave him the address, and they were soon on the smooth Coast Highway travelling south.

“You’ve had time for a little research, Bob,” Jupiter said. “What can you tell us about dragons?”

“A dragon,” Bob said, “is a mythical monster, usually represented as a large reptile with wings and claws, breathing out fire and smoke.”

“I haven’t done any research,” Pete interrupted. “But I think Bob left out something important. Dragons are not friendly.”

“I would have mentioned that, too,” Bob said, “but Jupiter is interested only in facts. Dragons are mythical, which means they aren’t real. So if they aren’t real, we don’t have to worry if they’re friendly or not.”

“Exactly,” Jupiter said. “Dragons are creatures of the legendary past. If there ever were any actual ones, it would seem they’ve all been eliminated by the due processes of evolution.”

“That’s fine with me,” Pete said. “So, if they’ve all been eliminated, how come we’re on our way down to investigate one?”

“We heard that five dogs have disappeared within the past week in the peaceful town of Seaside,” Jupiter said. “And Mr. Hitchcock told us that a friend of his lost his dog and saw a dragon near his house. Doesn’t that suggest anything to you?”

“It sure does,” said Pete. “It suggests I should be back in Rocky Beach surfing on my board instead of coming along with you to catch a dragon.”

“If Mr. Hitchcock’s friend, Henry Allen, engages our services, then it will be a profitable adventure for The Three Investigators,” Jupiter said. “Why don’t you try to look at it that way?”

“I’m trying, I’m trying,” Pete said.

“Whether there is a dragon or not,” Jupiter said, “something mysterious is apparently going on. Soon we will have facts to work with. Meanwhile we’ll have to approach the matter with an open mind.”

They had reached the outskirts of Seaside, and Hans slowed the truck as he searched for the street number Jupiter had given him. They travelled slowly another mile and then Hans stopped. “I think this is your party, Jupe,” he said.

All they could see was high hedges and palm trees. If a house was there, it seemed to be hiding.

Pete spotted the small sign on a white letterbox.

“H. H. Allen,” he read. “This must be the place.”

The boys piled out. “This preliminary investigation should take approximately two hours, Hans,” Jupe said. “Can you make your collection and delivery and come back for us then?”

“Sure thing, Jupe,” the husky Bavarian said. He waved and swung his truck round to head down a steep road that led to the centre of the town.

“Let’s take a quick look round first,” Jupiter said. “It may help if we’re better orientated when we speak to Mr. Allen.”

Houses were strung out along the high ridge overlooking the Pacific. The neighbourhood had a lonely, deserted air. The boys walked to a piece of vacant ground next to the film director’s house and looked down.