The Witch-king has an Idea
The Witch-king gave a dreary sigh. "Alright, Ringwraith #4, tell me your crazy plan."
"Well, sir, you see those bean plants over there? In the field?"
"Those weeds? How do you know they're bean plants?"
"Because I like plants."
"Nerd."
"Anyways, as I was saying, we can harvest the beans of those plants and feed them to the orcs, making gas. If we can collect this lighter-than-air gas, we can fill a balloon with it, tie it to the city, and we can float over the mountains. Why need tyres, when we can float in the air?"
"That's a stupid plan, and needlessly gassy. And why did you say tires with a Y instead of an I?"
"I did not."
"Yes you did, I heard you myself."
"Well whatever I said, what do you think we should do, if you are so disapproving of my plan?"
"I think we need help from the other seven."
'The other Ringwraiths?"
"No, the seven Fathers of the Dwarves," said the Witch-king. He rolled his eyes sarcastically. "Of course I mean the other Ringwraiths, idiot. Just let me summon them. Stay here and don't touch my chair."
The Witch-king entered the highest tower, and climbed up the spiral staircase up to the chamber of the Ithil-stone, and from there he used a ladder to crawl through a trapdoor in the ceiling. And once through that trapdoor, he was on the roof of the highest tower.
"GET OUT OF MY CHAIR!" he shouted at Ringwraith #4 far below. Ringwraith #4 sprang out of the armchair as though he had sat on an iron spike.
"Better!" shouted the Witch-king. Now he got back to the task at hand. On the roof was a great read lever, labeled
Only Pull in Emergencies in four languages. He pulled this lever, and instantly a great roaring and shaking was heard and felt. Out of the highest tower burst a great pillar of roaring green flame, visible as far away as Erebor. "Mwahahahaha!" the Witch-king shouted. He hurried back down the tower.
"They're bound to see that beacon!" he said.
"But wh-why are you summoning the other Ringwraiths?"
"For their wingéd steeds, of course, you idiot! With all nine tethered to the city, they can lift us into the air and we can fly to our destination!"
"Isn't the city too heavy to be carried by our flying beasts?"
"Pfffffffff, no, as long as we lighten it a bit. We just throw the ugly furniture overboard, toss a few orcs over the sides, and voila! We're airborne. And we can always replenish our orc supply once we're in the mountains."
"Great plan, but how long will it take for the others to arrive?"
"Why do you ask so many questions? They'll be here in no time flat. In the meantime, you can go down to my chocolate vault and grab me a Khît-Khât bar." The Witch-king leaped into his armchair and shooed away Ringwraith #4, who glumly marched down to the dungeons and cellars to get the Witch-king his chocolate bar.