He took from Jupiter’s jacket pocket a folded white handkerchief with “J. J.” monogrammed on it.

“We’ll drop this for a false clue later,” he said. “Now follow me. Elena, you keep watch in the rear.”

He wrapped the rope around his waist, then led the way out into the hall. They moved swiftly but silently down the unlit stone hallway, then up a stairway to a still higher, pitch-dark hall.

Using his flashlight, Rudy located a door that was almost invisible in the dark wall. It opened with a loud squeaking of hinges that startled them all. But no alarm was raised; apparently no one was on these upper floors.

They slipped through like ghosts and went up a very narrow flight of stone steps. Another door led them out onto the broad roof of the castle. Stars glowed brightly in the sky overhead. A wall of stone surrounded the roof, cut at intervals with niches.

“Those were for shooting arrows, or pouring boiling oil down on attackers,” Rudy said, gesturing. “Nowadays everything is peaceful so the roof isn’t used for a look-out station any more. But there are still sentry huts at each corner. Over here.”

He led the way across the castle roof to a small, square stone building at one corner. Its wooden door opened with some protest. Rudy’s flashlight showed a dusty interior with four wooden benches that were wide enough to be beds, of a sort. There were narrow windows with no glass in them.

“Once sentries watched in shifts from each of these sentry huts,” Rudy said. “But those days are long past. You should be safe here until we can come for you, probably tomorrow night.”

Jupiter dropped down onto a wooden bench.

“I’m certainly glad the weather is warm,” he said. “But what is this all about, anyway?”

“Some kind of plot,” Elena replied. “You were to be arrested for stealing the royal silver spider of Varania, and somehow used to force Prince Djaro to give up the throne. That’s as much as we know. It’s all obviously nonsense, because you couldn’t steal the silver spider even if you wanted to.”

“No,” Jupiter said slowly. “We couldn’t have stolen it. But just the same, we have it. Show it to them, Bob.”

Bob put his hand in his jacket pocket. Then he tried the other pocket. Becoming alarmed, he tried all his pockets. At last he swallowed hard and said, “I’m sorry, Jupe, I don’t have it. In the excitement I must have lost it.”

“YOU HAD the silver spider and you lost it?” Rudy stared at Bob in dismay.

“That’s terrible,” Elena said. “But how could such a thing happen?”

Jupiter explained how Prince Djaro had told them the silver spider was missing, and asked their help in finding it. He told of Djaro’s taking them to the vault and showing them the imitation spider, and of his suspicion that Duke Stefan had removed the real one for purposes of his own — to prevent Prince Djaro’s coronation. Then Bob told how he had found the real spider hidden among his handkerchiefs.

“I begin to understand the plot,” Rudy muttered. “Duke Stefan had the spider hidden in your room. Then he sent men to arrest you. You were supposed to be found with the spider in your possession. Duke Stefan would claim you stole it, that Djaro by his carelessness gave you the chance. Djaro would be disgraced. You three would be expelled from the country and all ties with the United States would be broken off. Duke Stefan would continue to rule as Regent. Then, with Djaro still in disgrace, he would find some pretext for assuming the rule of Varania for himself.

“Now, though the spider is gone, he can still proceed. He will charge you with stealing it and hiding it, even if we manage to get you safely to the American Embassy.”

Pete shook his head. “I still don’t understand,” he said, “why the silver spider is so important. I mean, suppose it had been lost in a fire or something, then what?”

“Then the whole country would go into mourning,” Elena put in. “But Prince Djaro would not be blamed. Really, it’s hard to explain what that silver spider of Prince Paul means to us. It’s not just a jewel. It’s a symbol. It represents all we treasure — our freedom, our independence, our good fortune.”

“Probably we’re superstitious,” Rudy added. “But a legend goes with it. Prince Paul is supposed to have said, when he was crowned, that just as a spider had saved him and let him bring freedom to his people, so would freedom and fortune reign as long as the silver spider remained safe. Maybe he didn’t actually say that, but every Varanian firmly believes he did. The loss of the spider would be a national calamity. To make Prince Djaro responsible for the loss, even indirectly, would make the citizens of our country, who now love him, feel he is unworthy.

“No,” he finished, after a long pause, “unless we can restore the silver spider to Prince Djaro, Duke Stefan will win.”

“Golly,” Bob said, gulping, “that’s bad. Here, help me look again. Maybe I missed it.”

This time Pete and Jupiter searched Bob’s pockets, turning each one inside out. They even looked in the cuffs of his trousers. But they knew as they did so it was hopeless. Bob didn’t have the spider.

“Think, Bob!” Jupiter urged. “You had it in your hand. Now what did you do with it?”

Bob frowned, trying to think.

“I don’t know,” he said. “The very last thing I can remember is the pounding on the door and Rudy coming in the window. Then everything is a blank until he was bending over me on that balcony.”

“Partial amnesia,” Jupiter said, pinching his lip. “When someone gets a blow on the head, it isn’t at all unusual for him to forget what’s just happened. Sometimes he forgets everything for the last few days or even weeks. Sometimes just for the last few minutes. Usually his memory for the missing time gradually comes back, but not always. That’s apparently what happened to Bob. When he bumped his head on the balcony, he forgot the last three or four minutes.”

“I guess that’s what happened, all right,” Bob sighed, feeling the bump on his head. “I have a kind of recollection of running around the room, trying to find a good hiding place for the spider. I was pretty excited, of course, but I do remember thinking it wasn’t any good to hide it under the mattress or under the rug, or back of the wardrobe, because it would be found at once.”

“The natural thing to do,” Rudy ventured, “would be to jam the spider into your pocket when you saw me. Then maybe it fell out when you tumbled off the rope on that balcony.”

“Or maybe I still had it in my hand when I hurried out onto the balcony,” Bob said unhappily. “Then when I started feeling my way along the ledge, I might have just opened my hand and dropped it. It could have fallen on the ledge or maybe down into the courtyard.”

“If it fell into the courtyard, it will be found,” Rudy said, after a long silence. “If so, we’ll know about it. If it isn’t found — ”

He looked at Elena. She nodded.

“Duke Stefan’s men probably won’t search your room for it,” she said. “They’ll think you three still have it. So if it isn’t found in the courtyard, tomorrow night we must go back and look for it.”