Cold Storage

That was when Hero saw what they’d come for. There, at the far end of town, in front of one of the best kept of the very modest houses, was a silver metal tank, its finish recently polished to a bright and reflective shine.

“I don’t think that’s from here.”

They walked toward the tank, wary. The wind swirled harder, and the dust in the air billowed around the houses, rearing up in columns in front of them before dust-deviling back to the ground in a corkscrew and moving on. It was getting hard to see.

“Stop here.” Hero held a hand out when they were still ten feet from the tank. She scanned the ground around them as best she could in the billowing sand, then continued on, searching the ground carefully before she placed each step.

“Walk in my footsteps.”

They did, following her in single file, careful to place their feet directly onto her boot prints as they went.

Hero reached the tank and squatted down. She saw the fungal covering immediately, but only because of her practiced eye. An untrained observer wouldn’t have perceived anything more than a greenish patch on the rounded surface of the tank, a bit like oxidized copper. The tank wasn’t in pristine condition anyway; it had made an uncontrolled re-entry into Earth’s atmosphere, after all, that’s going to put a few dents in anything. But to Hero, the unremarkable greenish patch read like a semaphore.

Trini looked around them, still with her gun at the ready, just in case. She took a few steps toward the house, watching where she walked. She stopped, studying the building, which wasn’t very different from the other ones. But there was one thing she noticed—the car. An old Dodge Dart, it was parked at an odd angle to the house, its hood pushed almost right up against a porch pillar. The porch had a low-slung, corrugated roof that bent down at an angle, and from where the car was parked it wasn’t a very big step up from the hood to the roof. Trini looked up, thinking.

Back at the silver tank, Hero bent down, pulling her sample case around in front of her. She clicked it open, snapped out a 20x magnifying lens, and squeezed it to activate the LED lights around the edge of the beveled glass. Through the lens, she got a closer look at the fungus. It was alive, all right, and florid, visibly seething even at this magnification. She leaned as close as she dared, looking for active fragmentation. There was movement there, and she wished like hell she had a more powerful magnifier, but twenty power was the most the field kit carried, which meant she had to get closer still.

She looked back, over her shoulder, at Roberto.

“Slide your hand through the loop in the suit between my shoulder blades.”

Roberto looked down. There was a tight vertical flap of fabric sewn into the back of the suit, a handle of sorts, with just enough space to get his fingers through. He did as she asked.

“Now hold on tight,” she said. “I’ll pull against you, but don’t let me go. If I start to fall, give me a hard pull back. Don’t be shy about it. Don’t let me touch it.”

“You got it.”

He held on tight. Hero braced her feet just short of the tank, about a foot away from it, and leaned forward, putting the magnifying glass and her mask as close to the surface of the middle of the tank as she possibly could. Roberto hadn’t expected her to have quite as much confidence in him as she apparently did, and he swayed a little as she let her weight fall forward. But he was strong and recovered quickly, resetting his feet and holding her steady.

The faceplate of Hero’s helmet moved to within three inches of the surface of the tank, she switched the lens to max magnification and close focus and flicked the LEDs to their brightest setting.

She gasped. Through the lens, even at this minimal magnification, she could clearly see fruiting bodies sprouting off the mycelium, stalks with a capsule at the top, swelling at their seams with ready-to-spread spores. The mycelium’s growth was so fast it was visible.

“Jesus Christ.”

Roberto couldn’t see around her bulky suit, and the curiosity was killing him. “What is it?”

Hero couldn’t tear her eyes away.

“I don’t know, but it’s huge, and it’s fast. And heterotrophic; it’s got to be pulling carbon and energy out of everything it touches, otherwise there’s no way it …” She trailed off, staring at something intently.

“No way what?”

Hero didn’t answer. She was fascinated by one of the fruiting bodies. Its capsule was bloating beneath the lens, ballooning up off the surface of the tank.

“This is the most aggressive sporing rate I’ve ever—”

With a sharp pop, the entire fruiting body burst, and the lens of the magnifying glass was flecked with microscopic bits of goo. Hero shouted and involuntarily lurched backward, away from the tank. She was more startled than frightened but lost her balance for a moment and threw her right foot out to the side to steady herself. Her boot squished through something soft before finding solid ground next to the tank, but it was too little too late; she was past the tipping point and on her way down, right into whatever she’d just stepped in. She watched as the ground moved up toward her in slow motion.

And then she was moving upward again. With one strong, controlled tug on the loop at the back of her suit, Roberto pulled her onto her feet next to him.

She looked up at him, grateful.

He smiled. “Careful.”

A voice called from nearby. “Hey.”

They turned. Trini was standing on the roof of the house, about ten feet above them. “I found Uncle.”

It wasn’t much of a climb, even in the suits. First onto the hood of the car, then one big step up onto the porch roof, then a sort of jump with a shoulder roll, and they were all the way up. Roberto went last, so he could give Hero a shove up onto the roof if needed, and he was so preoccupied with making sure she didn’t fall that he failed to notice the sole of her boot, even when it passed within a foot of his face. He would have had to be pretty eagle-eyed to see it anyway, because there wasn’t much of the stuff, but it was there.

Near the heel, between the fourth and fifth hard rubber corrugated ridges of her right boot, there was a smear of green fungus she’d picked up when she lost her balance back at the tank.

Hero scrambled the rest of the way over the edge of the roof, Roberto flipped himself up to join her, and they walked the few paces over to where Trini stood looking down at something. The wind and dust had picked up substantially, so her view was partially obscured, but Trini knew a human corpse when she saw one. This one was in rough shape. Uncle couldn’t have been dead for all that long, but the damage to his corpse was extensive, and it wasn’t postmortem. The flesh wasn’t mangled from the outside, by scavengers or weather.

“He exploded,” Hero said.

Boy, did he ever. What used to be Uncle was now a husk that had been turned inside out, everything internal made external. His rib cage was wrenched open cleanly and violently at his sternum, parted like a suit coat lying on the floor with nobody in it. His arms and legs were denuded of flesh, their bones pockmarked with what looked like more tiny explosions from within, and the plates of his skull had been split apart along their eight seams, as if the glue that held him together suddenly failed all at once.

Roberto, who had seen a lot of ugly things, had never seen anything like this. He turned away, and as he did so the wind let up, the dust cleared for a moment, and all at once he had an unimpeded view looking back the way they’d come. Every building in town was more or less the same height, and from up here on top of Uncle’s house, he could see onto all the other rooftops.

“Oh my God.”

The others turned and saw what he saw.

The rooftops were covered with dead bodies, every single one of them burst open in the same way as Uncle’s.

Roberto didn’t need to count to know there would be twenty-six.

AT THE MOMENT THEY STOOD ON THE ROOF, PIECING TOGETHER WHAT had happened to the residents of the doomed village, the fungus was busily at work between the corrugated rubber ridges of Dr. Hero Martins’s right boot. Cordyceps novus had reached a barrier, the hard rubber sole between the boot and her foot, and if there was one thing it hated, it was a barrier. But every good villain has a henchman.

In its mutated state, the fungus housed an endosymbiont, an organism that lived within its body in a mutualistic relationship. What the fungus couldn’t do, the endosymbiont could—in this case, catalyze the synthesis of random chemicals in a special new structure in order to break through barriers. It was like having your own chemistry set.

The endosymbiont, which lived on the surface of the fungus in the form of a light sheen, was exposed to the atmosphere every time Hero took a step. It absorbed as much oxygen as it could, combined it with carbon drawn from the dust and dirt particles that had stuck to the goo, and formed a tight network of carbon-oxygen double bonds. These carbonyl groups, now active ketones, pushed their way upward, toward the sole itself, until stopped there by the hard, unyielding mass.

So it hybridized again. The new ketone sampled available elements from the rubber and dirt and dust and cycled quickly through a variety of carbon skeletons. It mutated into oxaloacetate, which is great if you want to metabolize sugar but no use getting through the sole of a boot. Undaunted, it mutated again, into cyclohexanone, which would have been good for making nylons, and then into tetracycline, superb if you’re fighting pneumonia, and then, finally and most damagingly, it recomposed itself as H

FSbF

—fluoroantimonic acid.

The powerful industrial corrosive began eating its way through the rubber bottom of Hero’s boot.

The mutation process so far had taken just under ninety seconds.

Hero, of course, was unaware of what was happening. As they climbed down from the roof and hurried back to the tank, she was distracted, trying to explain what they had just seen. The fungus, she speculated, was mimicking the reproductive pattern of Ophiocordyceps, a genus that consisted of about 140 different species, each one of which reproduced by colonizing a different insect.

“How’s it do that?” Trini had her gun out again and her head was on a swivel as they climbed down onto the roof of the car.