“What’s he talking about now?” Pete asked Bob. Jupiter pointed across the street.

“There were two neighbours Mr. Allen mentioned who did not own dogs. We met the first one, Carter. Now we have a few questions to ask the other one, Arthur Shelby.”

A closed metal gate running chest high barred their way. The boys looked over it to the large house set back on the property of Mr. Arthur Shelby.

“Looks okay,” Bob said. “I don’t see a cannon emplacement anywhere.”

Pete inched a little closer to look at the windows on the lower and upper storeys. “I don’t see anybody watching us,” he said. “Maybe Mr. Shelby isn’t home.”

Jupiter stepped forward. “It’s easy to find out,” he said. “All we have to do is go through this gate, and — ”

He stopped, open-mouthed. His companions gaped too. The gate had opened without Jupiter touching it.

“How did you do that?” Pete demanded. “You developing magical powers?”

“Maybe the wind blew it open,” Bob suggested.

Jupiter shook his head. He held out his arms, stopping his companions from advancing, and stepped back. The metal gate swung shut.

Jupiter took a step closer. The gate opened.

“A very simple explanation,” he said. “The gate works on an electronic seeing-eye principle. You’ve all seen that at airports, supermarkets and other modem buildings.”

Pete looked at the gate sceptically. “Sure I have,” he said. “Only I’ve never seen one in a private house before.”

“Any sign of progress and modernity is a good sign,” Jupiter said cheerfully. “The fact that Mr. Shelby uses such a device on his gate shows he is not superstitious or hidebound by convention. Just the kind of person we want to talk to, especially about such an unlikely topic as a dragon in the neighbourhood.”

He stepped through the gate and the other boys followed. Off to the side of the path, the boys saw a large, ornate sundial set in the centre of the lawn. Ahead of them was a large flower laden trellis. They walked under it.

Suddenly the trellis dropped.

The boys stopped, bumping into each other. The front part of the trellis had dropped in front of them. Behind them, the back part of the trellis hissed downwards with a slight clanging sound, barring their retreat.

They were trapped in a huge metal cage decorated with flowers!

“I hope this is only a joke,” Jupiter said, licking his lips nervously. “It’s like a portcullis.”

“What’s a portcullis?” Pete asked in a panicky voice.

“It was usually a large, heavy iron grating suspended by chains and lowered between grooves to bar the gateway of a castle or fortified town,” Jupiter explained.

“I’ve seen pictures of them in old books at the library,” Bob said excitedly. “It’s usually the last defence after you cross the moat of the castle.”

“I don’t remember crossing any moat,” Pete complained fretfully.

There was a slight hissing sound, and as suddenly as it had fallen, the trellis lifted above their heads. The boys looked at each other.

“I think Mr. Arthur Shelby has a keen sense of humour,” Jupiter said, relieved. “Let’s go.”

He took a step forward and Pete grabbed his arm. “You’re going the wrong way, Jupe,” he said. “Maybe they don’t want us in this castle.”

Jupiter shook his head, smiling. “First an automatic-opening gate. Then an electronic controlled trellis. Mr. Shelby seems to be unusually preoccupied with scientific gadgets. It would be a shame not to meet him.”

Jupe moved forward again and his companions followed reluctantly. He grinned as he stepped up and pressed the doorbell,

“Yow-wh!” he yelled, and leaped back, shaking his arm. “That doorbell has an electric charge on it! I got a shock!”

“Okay, I’ve had enough of this Mr. Shelby’s jokes,” Pete said. “I vote we call off the interview with this joker right away.”

“I’m with Pete,” Bob said. “I’ve got a funny feeling Mr. Shelby is trying to tell us he doesn’t want us here.”

“I don’t think so,” Jupiter said. “He’s testing us. He’s put us through a sequence calculated to scare us off.”

As if in answer to Jupiter’s reasoning, the front door clicked and swung silently open.

“Neat,” Bob said admiringly. “He’s got this place bugged all around.”

The boys cautiously stepped over the threshold. The interior was dark and quiet.

Jupiter cleared his throat, trying to speak with confidence. “Good day, Mr. Shelby. We are The Three Investigators, calling at the suggestion of your next-door neighbour, Mr. Allen. May we come in, sir?”

There was no answer. Then faintly they heard a slight flapping sound. It came closer, and they heard it more distinctly. It appeared to be coming from high in the gloomy interior of the house. Suddenly they froze. A huge, dark form was hurtling towards them with a shrill whistling sound.

A big, black, hawklike bird, screeching fiercely, its sharp beak open, cruel talons outstretched, and eyes blazing madly, swooped down on them!

“Duck!” Pete yelled.

The boys flung themselves to the floor.

The screeching bird plummeted towards them, its huge talons curled menacingly.

Then it slowed to hover a foot above them. Surprisingly, it remained there.

The shrill screeching sound stopped.

Jupiter had flung his hands over his face to protect his eyes. He peeked cautiously between his fingers. Then he sat up, his expression changed from fear to chagrin.

“It’s okay, fellows,” he said. “It’s not a real bird.”

“What?” Pete cried.

He lifted his head unbelievingly. Bob did the same.

The dark bird hung there limply, dangling at the end of a thin copper wire. Its yellow eyes glared at them with a dull expression.

“It’s a toy,” Jupiter said. He reached out and touched the bird. “Seems to be made out of plastic and chicken wire!”

“Oh, boy!” Pete said disgustedly.

From the dark interior of the room came the sound of rasping, breathless laughter. Lights flashed on suddenly overhead.

A tall, thin man wearing dark overalls stood there looking down at them. His hair was short and coppery red.

“Welcome to Mystery Castle,” he said in a deep and sepulchral voice.

Then he doubled over, laughing. His laughter became riddled by a spasm of coughing.

“He’s sure got a keen sense of humour,” Pete muttered.

The tall, red-headed man straightened up slowly. His blue eyes were bright and watery. “Arthur Shelby here. I’d better take my bird back before it bites you.”

The boys scrambled to their feet. The man came closer, stooped and unhooked the wires holding the motionless bird. Jupiter looked up at the ceiling and smiled

“He had it running on those narrow-gauge tracks up there,” he said. “Just like electric toy trains.”

Bob and Pete looked up at the tracks stretching across the ceiling. “I like electric trains better,” Pete said. “They don’t scare me.”

Mr. Shelby was grinning. “Fooled you, did I? Sorry. It’s my hobby — making crazy gadgets,” He waved his hand to the room behind him. The boys saw a large workshop cluttered with tools and scraps of wood and wire.

Mr. Shelby set his bird down on a work table. His voice was normal now, not deep and mournful, merely husky. “What brings you boys here?” he asked.

Jupiter handed Mr. Shelby one of their business cards. “That may explain it, sir,” he said. “We like to solve mysteries.”

The red-haired man studied the card, making no comment about the question marks. Then he returned it, smiling.

“I suppose the mysteries round here are the missing dogs, eh?”

“When we learn all the facts of the matter,” Jupiter said slowly, “it may turn out to be a single mystery. We’re trying to help Mr. Allen find his Irish setter. But I have a feeling his missing dog is linked somehow with the disappearance of the others in Seaside.”