“Incredible!” Mr. Hitchcock murmured. “The very real menace of a dragon that wasn’t real. I should like very much to hear about it.”
Bob Andrews whipped out his note book. He proceeded to tell how the investigation had run into a snag at the very beginning, and then how they had managed to pick up the threads that ultimately led to the solution of their original mystery. Mr. Hitchcock listened attentively.
“Your Mr. Shelby sounds like a most ingenious and interesting man,” he said. “Do I understand you correctly when you say he voluntarily gave up his foolproof plan to steal several million dollars’ worth of gold, rather than hurt you and some dogs?”
“Yes, sir,” Jupiter said. “He kept the dogs alive and fed them. He had to tranquillize them to keep them quiet and out of his way. He told us he was going to turn them all loose when he left the cave for the last time with the dragon and the gold.
“He could have forced us at gunpoint to help him carry out the gold after the Morgan brothers ran away. He could have taken enough to be wealthy. He didn’t need the entire ten million dollars.”
Mr. Hitchcock drummed his fingers on the desk. “And his original plan was actually to run the dragon underwater at night, in conjunction with those villainous Morgans?”
Jupe nodded. “I thought the dragon was too light, but he had calculated his ballast in advance — the heavy gold bars. He had to test his dragon in the water, at first, by loading it with rocks. As a matter of fact, that’s how your friend Mr. Allen happened to see the dragon. It was out on a test run, while he was looking for Red Rover.”
“And your clue to Shelby’s part in it was his cold?”
Jupe smiled weakly. “He had a bad cough when we met him. So I associated him with the coughing of the dragon. Later I found out it coughed when it stalled. That was partly due to wet wiring, from the many experiments in the sea.”
“But your mysterious phone call — the ghostly, rasping voice — that was really Shelby?”
Jupe nodded.
Mr. Hitchcock shook his head. “This Arthur Shelby doesn’t sound like a typical crook at all. How did he happen to tie up with such low characters as the Morgan boys?”
“They had a salvage rig and he knew them as tough men who would do anything. He needed their help for the work in the cave, drilling into the bank vault through the concrete wall of the tunnel, and then getting the gold out. When he offered them a million dollars, they were more than willing.”
“And how did they propose to get the gold from the sub into the boat?”
“After he got under way, the Morgans with their underwater gear were to attach a cable from the sub to their tug, and tow it out to sea. When they were far enough out, they were going to surface the sub and unload the gold bars. Then they were going to head for Mexico.”
Mr. Hitchcock nodded. “Why a dragon, at all?”
“That was from knowing your friend Mr. Allen and his film background, using dragons to scare people. You see, at first Shelby just thought it would be a new way to play a practical joke on his neighbour. But when he heard of a large shipment of gold bars to that bank, he decided to carry out a robbery. He figured the dragon could easily be converted into a functioning sub. It suited his kind of offbeat thinking — a funny and perfect way to get the gold from the bank through the old tunnel to the sea. It backfired on him because it was the oddity of the dragon that kept us interested in trying to solve the mystery.”
“I should have imagined Mr. Shelby to be without sufficient funds to construct something as elaborate as that dragon,” Mr. Hitchcock said.
Bob was ruffling through his notes. “I left out a page,” he explained. “He told us he had friends working at some of the studios. Some of them liked to make gadgets like he did. They told him of a prop dragon that was to be destroyed to make room for other properties needed in storage. He saved them the trouble, went down and took it apart there himself. Then he had it hauled to his place in pieces and put it together later.”
Mr. Hitchcock frowned. “Did it have wheels?”
“No,” Bob said. “That was another bargain he picked up. He found an old abandoned chassis from a float at the Pasadena fairgrounds, left over from the Rose Bowl parade. They let him have it for towing it away. He put the dragon on that.”
“Hmmm. Clever,” Mr. Hitchcock said. “Now, how was it that Shelby knew about the big cave and the tunnel, whereas my friend Allen, who lived almost directly over them, did not?”
“Well, to begin with, Shelby knew about the existence of the tunnel from his days as an engineer for the City Planning Board. But he only found a way into the tunnel by accident.
“A landslide from an earthquake had covered the big cave many years before either he or Mr. Allen lived there,” Jupe continued. “Shelby was walking along the beach one day and saw a fissure in the rock wall. He dug in and discovered the cave and then the tunnel. He told the Morgans. They helped him build the fake wall inside. It was to fool people who accidentally found their way into the cave, and stop them from going farther into the tunnel.”
“I assume they helped him make the fake rocks outside the entrance, too?” Mr. Hitchcock said.
“Yes,” Jupe said. “That was interesting, and well thought out, too. They had to work from the inside of the cave and not attract attention. It was only when they had it all constructed that they could afford to clear the outside rubble away, at night, and insert their own rock covering.”
Mr. Hitchcock nodded. “The Morgan brothers — were they responsible for the collapsing staircase on your first adventure there?”
Pete interrupted. “They didn’t want anybody around who might spoil their scheme, so they weakened that staircase to scare people off the beach. They spotted us from their boat when we fell down it. And when we didn’t leave, they came out of the ocean and pointed their spear guns at us. They figured that should frighten us into not coming back.”
“I see,” Mr. Hitchcock said. “I believe you mentioned they had disappeared in the original cave you entered. Did you solve that mystery?”
Bob was back to his missing page of notes. “They went down the same pit I fell in. It wasn’t quicksand. Just a lot of mud and water. With their gear, they were able to work their way through to an underground passage that came out in the other cave near the tunnel. Like cave diving. It was an alternative way into the large cave during the day. They couldn’t take a chance of disturbing the big rocks outside too much and possibly attracting attention. Incidentally, after they ran out of the cave that last night, they never came back. I guess they were ashamed of being scared.”
“And good riddance, I might add,” Mr. Hitchcock said. “The thin, reedlike object Shelby blew into, that made no sound but opened and closed the fake cave wall. Am I to assume that was a sonic contrivance?”
jape nodded. “It opened and closed the prop rock opening outside, too. It had two varying high-frequency sounds. But it was Mr. Shelby’s undoing actually.”
“Indeed, young Jupiter!” Mr. Hitchcock exclaimed. “How was that?”
“It was his experimenting with the silent whistle, his sonic beam, that attracted all the dogs to him in the first place. As you know, sir, dogs can hear a higher frequency wavelength than humans. Mr. Allen’s setter ran to him the first night it was released from the kennel. He didn’t expect that because he thought Mr. Allen was still in Europe. That meant he had to move fast. The other neighbourhood dogs had already deserted their owners at night and run to Mr. Shelby’s sonic whistle. He couldn’t get rid of them, and had a lot of work to do, getting the dragon ready, the bank-vault opening drilled and the tunnel tracks cleared to the bank. Rather then destroy the dogs, as the Morgans wanted, he merely put them to sleep by adding tranquillizing agents to their food.”
Mr. Hitchcock reflected some more. “The dragon roared, you said. Was that your imagination running wild, lads?”
Bob shook his head. “No, sir. That roar and a lot of other things, like a windscreen opening in front were controlled by instruments on the dragon dashboard. Jupe was pressing all the buttons he could find in order to get it going.”
“Now, this Mr. Carter,” Alfred Hitchcock asked, “did he get safely out of the cave after being bowled over by the escaping dogs?”
“Yes,” Pete interrupted. “He was gone when we went back there to pick up the equipment we’d left
