“Hey, Sam,” said Pif. She was surrounded by ornamental tea lights, her pen nib scratching over the page she was working on. “Almost done.”

She kept writing. Petrovitch borrowed one of the candles and carried it over to his desk. He started pulling out his drawers one by one and sorting through them. He found the night-vision goggles he’d taken from the Paradise militiaman, and his second-best pair of glasses.

The ones on his face had become part of him; the scab that covered the top of his ear also contained the spectacle arm. There was nothing for it but to break it free. It left him more breathless than he was already.

Pif put down her pen and sorted her papers out into two piles, each of which she folded in half and slid inside identical envelopes.

“That’s that,” she said, and finally looked up. “Sam. What have they done to you?”

“Yeah. You should see the other guy.” He eased on his spare glasses. He could see properly again. “We need to talk.”

“Yes,” she said, holding up one of the plain brown envelopes. “You need to take this with you.”

“Sure.” He nodded.

“It’s a mostly complete solution to the theory of everything. I’ve done as much as I can on it, but I have a feeling if I wait any longer, I won’t have time to make a copy. Now, I have some undergrads scavenging parts for a short-wave transmitter, but otherwise it’s up to you to get it out of the city.”

“Me? Pif, you don’t know…”

She held up her hand, and her palm shone in the candlelight. “We’re going to try and hold the university for as long as we can. The gangs we should be able to fight off. But those… things. We can’t stand up to them.”

“About those,” started Petrovitch, but she cut him off.

“Sam! We’ve solved the biggest problem in science for two centuries. If the proof stays here, it’ll die with us. This,” and she hit the papers with the back of her hand, “this is the most important thing in the whole world.”

“Stanford’ll work it out. Or Bern.”

“Fuck Stanford,” she yelled. “It’s our work. And there’s no guarantee of anyone ever finding this solution ever again. Three words: Fermat’s Last Theorem.”

“He lied. He didn’t have a proof. Group theory wasn’t even around in the seventeenth century.”

“How do you know? The idiot didn’t write anything down, and it took us three hundred years to do it differently.” She strode over to Petrovitch’s desk and slapped the envelope down in front of him. “Get it out of the city. Any way you can.”

“Pif,” he said, “if I had the rat, which I did for all of half an hour earlier on today, I’d try and mail it to UNESCO straight away.” He picked up the envelope and felt the weight of it before he slid it in his inside coat pocket. “I have something else I have to do. Something even more important than this.”

She stared at him as if he was mad.

“Okay. Listen, because that short-wave radio of yours is going to work and if I screw up, the outside world needs to know this: the AI known as the New Machine Jihad has its physical location in a vault below the Oshicora Tower. The vault is rad- and emp-hard, and I have to assume it has its own uninterruptible power supply. It has to be destroyed. I don’t know if it can migrate to another host, or whether it already has, but if the sun comes up and it’s still in control, someone’s going to have to nuke it.” He raised his filthy bandaged hand and nudged his glasses back up his nose. “Preferably from orbit. It’s the only way to be sure.”

“Sam,” said Pif, “what about science?”

“I think trying to save the world trumps even science.”

She knelt down next to him. “These equations will save more than the world. They’re going to open up the universe to us. Fusion power. Bias drives. Black hole engines if we can find something strong enough to hold one. Space elevators. O’Neill habitats. Generation ships. Colonies on Mars, around Jupiter, in other systems. Flying cars, Sam. You finally get flying cars. And they’ll all be named after you: the Ekanobi-Petrovitch laws.”

He swallowed. How would he do it? Top-of-the-range electronics shop, one that hadn’t already been stripped clean? Charge up the battery pack? Physically take the information with him, maybe. Find a boat dragged loose from its moorings by the rising river and head for mainland Europe. How long would it take? Half a day?

Petrovitch sighed. He scooped up the night-vision gear and held the goggles to his face. She appeared green and anxious on his screen. “Sorry, Pif. The moment I can, I’ll get the proof away. The moment you can, get them to hit the Oshicora Tower. It’s the best I can do.”

She patted his arm. “Good luck, Sam.”

“And you.”

He pushed his seat away and walked to the door.

“Sam?”

“Yeah?”

“An AI? Really an AI?” she asked. “And it phoned you up here?”

“Yeah. Yeah, it did.”

She grinned. “How cool is that?”

Petrovitch started to laugh. It hurt, it hurt everywhere. “It’s pretty cool,” he admitted. “Now I have to go. Maddy’s waiting for me.”

34

The car rolled to a stop at the edge of the flood. Madeleine pulled on the handbrake, and ran her fingers through the wires under the steering column. The engine spluttered on for a few seconds, then shuddered to a halt.

Water lapped around the base of the monumental arch where Petrovitch had stood just that morning. He realized how many hours ago that was, standing in the morning cold without a coat and only the homeless for company.

Now he was back, armed with nothing but his wits and some equations. But he did have Madeleine, night-vision goggles pushed up onto her forehead. He groped in the footwell for the steel pipe, and passed it to her.

“Did you ever feel so incredibly underprepared?” he asked.

“I’m only nineteen. I haven’t really had that much experience,” she said. She kicked the door open and stepped out. Water pooled around her feet.

Petrovitch reached through the missing window for the door handle and leaned against the frame. It popped free, and he half-fell, half-crawled from the interior.

“No sign of the riot wagon. If they’re not here, we’re screwed.” He turned his gaze on the Oshicora Tower, which was lit from within and from without. Sealed floodlights made bright circles in the filthy water, and the glass of the tower glittered like tinsel. Up it soared, story after story of blazing light, until it reached the park at the very top, which shone like a great jewel.

Everywhere else was dark, making the tower seem like a fairy castle rising from a lake, full of feyness and eldrich wizardry.

Madeleine slipped the goggles down over her eyes, and scanned the way ahead. “There’s nothing moving.”

Petrovitch took a deep breath. It didn’t help. “Where the chyort is Chain? If he’s going to kidnap the one person we need, at least he should have the decency to bring her along.”

“Perhaps the Jihad has made another mistake. Perhaps they’re all dead.”

“That would be just great.” He waded out into the black water. Things barked against his shins, and he tried not to imagine what they might be. “Come on. Stick to the left where it’s shallower. There’s an underpass around here, and we don’t want to fall in.”

Her hand shot out and grabbed his arm. It forced his shoulder and he saw stars. “Sam. It’s alive.”

“What is?”

“This… everything!”

He reached up with his bandaged hand and dragged the goggles down off her face until they hung glowing around her neck. “Yeah. Rats. They’ve come to eat the bodies that are choking the ground floor of the tower. I was going to tell you about those, but not until we got to them.”

“Sam,” she started.

“It’s not like they’re going to be hungry, is it?”

“I suppose it depends on how many rats there are.”