“Quickly now!” he said. “The other guards up the corridor will hear. We must move fast. Jupiter, bring the other lantern. Follow me!”

Rudy was already moving down the corridor, toward the pitch-darkness of the lower dungeons. Bob and Jupiter raced to follow, the electric lantern making bobbing beams of light ahead of them as they ran.

They came to some stairs, ran down them, and stopped. Rudy was bent over, tugging at a big iron ring in the floor. By the light of the lantern, they saw an ancient, rusty manhole set into the stone floor.

“It’s stuck!” Rudy gasped. “Rusted. I can’t budge it.”

“Quick!” Jupiter said. “The rope. Put it through the ring and we’ll all pull.”

“Yes, of course!” Rudy whirled around, spinning out of the blanket rope wound about his waist. He pulled one end through the ring. All three boys seized the rope and pulled. At first the cover wouldn’t budge. Then, as they heard shouts and trampling feet behind them, they gave one tremendous heave.

The manhole cover flopped up and fell with a clang on its side, revealing a pitch-black hole from which came the sound of rushing water.

“I’ll go first,” Rudy gasped, pulling the rope loose. “We’ll all hold on to the rope. No chance to put the cover back.”

He lowered his feet into the hole, put the handle of the electric lantern between his teeth and, still holding the blanket rope, dropped from sight. Bob followed him. He didn’t like the look of the hole or the sound of water underneath, but he didn’t have time to hesitate.

There was an endless moment in which he was falling through nothing. Then he landed on the bed of the ancient storm sewer. It was a fall of only about six feet and he wasn’t hurt, but he would have fallen into the knee-deep water if Rudy had not caught him.

“Steady!” Rudy whispered. “Here comes Jupiter. Get out of his way.”

Jupiter was less lucky. Before they could grab him, he lost his balance and sat down in the flowing water. Rudy grabbed his shoulders so he did not go under completely.

Puffing, Jupiter scrambled to his feet.

“It’s cold!” he said.

“Just rain water,” Rudy said swiftly. “We’ll be wetter before we get out of here. Come on, follow me. Everybody hold on to our rope. The water is flowing toward the river, but where they meet there are heavy iron bars. We couldn’t get out that way so we must go upstream.”

Shouts and angry voices echoed above their heads. A lantern flashed down from above. But the boys were on the move already. Stooping, for the rounded roof of the sewer was too low for them to stand upright, they began to hurry through the swirling water.

The manhole and the voices and light receded behind them. Soon their tunnel met a larger one, and they could stand upright. They sloshed along, clutching the rope, the two electric lanterns giving out a little light but not enough to combat the total darkness in which they moved. Bob and Jupiter heard squeaking noises and something furry, swimming, was swept against Bob’s leg. He gulped but kept walking.

“The guards will follow us!” Rudy shouted. “They’ll have to for fear of Duke Stefan. But they don’t know these sewers and I do. There’s a place up ahead where we can grab a minute’s rest.”

He almost pulled them along as he went. Now the water seemed deeper. They passed a place where it came down from above like a waterfall, thoroughly wetting them.

It must be a drain in the streets above, Bob figured.

They waded on, through another miniature waterfall, and then abruptly came out into a large round Chamber where four tunnels intersected. Rudy stopped and flashed his light around. They could see a ledge around the sides of the chamber, and iron rungs set into the rock, leading upward.

“We might get out here,” Rudy said. “But we don’t dare. Too close to the palace. We’ll rest on the ledge, though. I’m sure we have several minutes before any of the guards can catch up to us. They won’t be in any hurry to go through these sewers, you can be sure.”

Thankfully they scrambled up onto the two-foot wide ledge which partly encircled the chamber. There they stretched out, getting their breath.

“Golly, we did it!” Bob said finally. “Anyway, we got this far. But where are we?”

Rudy started to answer him. Then he stopped.

“Turn off the lights!” he whispered urgently.

They did so. Ahead of them in the tunnel was the faint gleam of a lantern, and it was obviously coming their way. Someone ahead of them, and the guards pursuing them from behind.

They were trapped!

“UP!” Rudy snapped. “We have to go up to the street. I’ll go first.”

He began to scramble up the wet, slippery iron rungs. Bob and Jupiter followed. They had to turn one lantern on long enough to find the rungs, then they shut it off and climbed in darkness.

Rudy reached the top. Holding tight with both hands, he got his shoulders beneath one side of the iron cover and strained upward. Slowly it raised. A crack of daylight came in. He got it up another inch until he could twist his head and look out. He gave an exclamation of dismay and let the cover back down.

“A patrol of guards right on the corner, waiting!” he whispered. “By the time we got the cover off and climbed out they’d have us.”

“Maybe we can hide up here,” Jupiter suggested, not very hopefully.

“It’s all we can do,” Rudy sighed. “Let’s pray they’ll keep on going.”

Beneath them a light glowed on the running water. Then, as they peered down, a very narrow rowboat came into view. A man sat in the rear pushing it with a pole. A girl sat in the bow, shining a powerful flashlight around.

“Rudy!” she called. “Rudy, where are you?”

“Elena!” Rudy cried. “We’re up here. Stay right there.”

The boat stopped. The light shone on them as the three boys scrambled down the iron rungs.

“Praise to Prince Paul!” Elena exclaimed. “We’ve found you. You did get away from them.”

While the man in the rear steadied the boat, the boys scrambled in. Instantly the man turned the boat around and began sending it back the way it had come with vigorous thrusts of the pole.

“The guard gave us a message that there were friendly rats in the sewer,” Rudy said to Elena.

“We’ve been looking for you for hours,” Elena replied. “We were afraid you could never escape. Oh Rudy, I’m so glad to see you!”

“And we’re glad to see you,” Rudy said with a grin. “This is my cousin, Dmitri,” he told the boys, gesturing to the man in the rear. Then he turned back to his sister.

“What’s happening outside?”

“No time to talk now,” Elena said swiftly. “Soon, when we can stop for a minute. Look ahead!”

Ahead of them a sudden shaft of daylight cut through the darkness.

“They’ve lifted the manhole cover!” exclaimed Dmitri. “They’re waiting for us. We’ll have to try to push through.”

He gave stronger pushes on the pole. The tiny boat shot ahead, into the shaft of daylight. The boys looked up. Guards were coming down into the sewer. One of them shouted, and tried to leap into the boat to overturn it. Dmitri swerved the rear sharply and the plunging guard missed. He went splashing into the water and went under, spluttering.

In another moment they were in the darkness of the gloomy tunnel again, moving swiftly beneath the city.

“They’ll follow us on foot, but they’ll be slow,” Rudy observed.

“More likely they’ll open up the covers ahead and wait for us,” Dmitri said. “Here’s a junction. I’m changing course.”

They had come to another large chamber where three great tunnels discharged their water. Dmitri swung the boat into the left tunnel, which was smaller than the others.