Free The Ringworld Throne by Larry Niven Page A

Vala’s eyes closed for an instant. Now it’s a problem, a challenge, and lesser species must see you solve it. Now I have you.
    The Ghouls had cleared the grass away from a sizable section of tent floor. They were drawing in the dark, tweetling at each other in their own high-pitched language. They argued over some feature none other could see, and settled that, and Harpster stood up.
    “When the shadow withdraws, you may examine these maps,” Harpster said. “For now let me only describe what you would see. Here, spin by port by two and a half daywalks, the ancient structure of an industrial center floats two tens of manheights above the ground.”
    “I know of a floating city,” Vala said.
    “Of course, near your Center City, a collection of free buildings linked. Floaters are rare enough these days. We think this one made machinery for the City Builders. Later it was abandoned.
    “Vampires have lived beneath the Floater for many generations, for hundreds of falans. The perpetual shadow is perfect for vampires. Locals moved out of their reach long ago. Peaceful travelers and migrations were warned to avoid it. Warriors must look to themselves in that regard.
    “This range of mountains to port and antispin of the Shadow Nest stands between there and here. It formed a barrier for the mirror-flowers. Hominids on the far side came to call it the Barrier of Flame, for the fire they could sometimes see playing along the crest.
    “The flowers would ultimately have crossed the crest and burned out the Shadow Nest in their usual fashion. Vampires wouldn’t be safe from horizontal beams of light. But then the clouds came.”
    Heads nodded in the dark. Harpster said, “The vampires’ range expanded by a daywalk. Grieving Tube is right, the damage is worse than that. Their population has grown, and hunger drives families of vampires into other domains.”
    Valavirgillin asked, “Can you blow away the clouds?”
    Both Ghouls hooted laughter. Grieving Tube said, “You want us to move clouds ?”
    “We beg.”
    “Why do you think we could do such a thing as move clouds?”
    Over the rising sounds of throttled laughter Valavirgillin said, “Louis Wu did that.”
    Harpster said, “Omnivore Tinker. Not odd as hominids go, but from off the Arch, from the stars. He had tools to prove what he said he was, but we do not know that he made clouds.”
    The Thurl spoke. “He did! He and the old Thurl boiled a sea to make these clouds above us—“
    “Then go to him.”
    “Louis Wu is gone. The old Thurl is gone.”
    “We cannot move clouds. Our embarrassment is great.” Harpster laughed. “What can we do that you cannot do yourselves?”
    The Thurl said, “We will use your maps, much thanks to you. I will lead an army of whatever species will fight. We will destroy this nest of vampires.”
    “Thurl, you cannot go,” Grieving Tube said.
    Harpster questioned. Grieving Tube began to explain, but the Thurl would not wait. “I am protector to my people! When we fight, I fight at the head—“
    “In armor,” the Ghoul woman pointed out.
    “Of course!”
    “You must not wear armor. Your armor keeps your smell. You, all who fight, you must wear nothing. Bathe where you find water. Wash every surface of your cruisers and wagons. Can’t you see that the vampires must not smell you?”
    Vala thought, Oh.
    “The bottleneck is the fuel,” Chitakumishad was saying. “The Reds make a beer, it can be turned into fuel—“
    “Go to your war by way of the Red pastures. We can send them the design for your distilleries by a secret means, tomorrow. Let them make fuel there while you make fuel here from your own stills and rotting grass. You will confront the Shadow Nest no more than a falan from now.”
    Chit nodded, his own mind busy with plans. “Fuel to take two cruisers there and back—“
    “You must cross the Barrier of Flame. I think your cruisers can do that. There are passes.”
    “Takes more fuel.”
    “Fuel to