In the center of a clearing in the forest was a camper van, and forming a circle around it lay a series of pots and vases from which a dense pink and yellow mist billowed in the calm morning air. Next to the van stood a folding table, three chairs and a beach umbrella; a girl no older than seven or eight sat on one chair, her attention on an old picture book of botanical illustrations, but abandoned it as soon as she heard the van’s door creak open. Two people walked out: a woman who appeared to be in her early forties, and a boy in his early teens. The three gathered around the folding table, where a series of colorful objects lay in small piles, each emitting a different faint light, and the boy began stashing some items of each group into a backpack: five yellow glowing marbles with orange specks, three blue spheres that shone purple when moved, six pink cubes that left a vanishing bright dust residue behind, and so on.

The girl reached towards a pile of light blue glowing pebbles and took a handful. “Don’t forget the blue peas”. She pointed out.

“I know. I packed some already,” the boy replied without looking at her.

She took a black orb with white swirls in her hands and offered it. “And the black smoke signal. I don’t think you packed one yet. You’re going inside a cave, but you should take one just in case.”

“Franzi, I know! I…” he stopped himself. His irritation wasn’t his sister’s fault, so he accepted the dark orb and packed it “…you’re right, I almost forgot it. Thanks”.

The girl smiled, showing a gap where two of her milk teeth had fallen out recently. He returned the smile, but the worry remained. He had to find crystals inside that cave or they would be in real danger soon. Coming back empty-handed wasn’t an option.

The woman, who had remained silent and focused on the mountain towering before them, now turned around. “You got everything? Want me to double-check for you?”

“No need to. Let’s go,” said the boy with a confident expression, and they all walked toward the edge of the circle of pots, with him going slightly ahead.

The girl quickly caught up and whispered in his ear, “Hey Stefan, did you two argue again?”

“No, we did not.”

“You shouldn’t argue. You know Rosario’s had a headache since yesterday,” she scolded him. “She’s only worried about you.”

They had set up camp right next to a steep mountain, part of a range that extended towards the west for as far as they could see. Between the mountain and the campsite lay a boulder field partly covered in moss and young trees, hinting the rockslide happened many years ago.

Since their arrival the day before, they had explored the boulder field and found evidence they were in the right place, and hidden behind the rocks lay an old road tunnel. In a piece of concrete which had probably been part of the entrance of the tunnel, but was now covered by vegetation, it was still possible to recognize the words: “Simmeflue II, 2300 m, construction year 2…” on a weathered plaque.

Despite being so close, the only passage they found that likely led inside the tunnel was too small for Rosario, the adult of the group, to fit in. And after a heated exchange that morning, she allowed Stefan, her oldest protegee and apprentice, to go in by himself.

Stefan checked his helmet, flashlight and knee pads, then tied a rope to his belt and walked inside the cave. He felt excitement and alertness growing as he sensed the cool and moist air of the cave. “Alright, see you in a bit!”

“Be careful, you hear me?” said Rosario, to which he only waved without looking back.

She tried to reassure herself that it would be fine; Stefan could still be a child, but he was familiar with this type of environment and knew how to handle himself. Still, Rosario had lived in a time when allowing a child to go into such a dangerous place alone was unthinkable for most adults. The persistent lightheadedness that had bothered her since the day before wasn’t helping, either. She was probably tired and needed a break.

Franziska’s voice brought her back to reality.

“Hey! Stefan forgot the green beans!”

The woman turned around at the same time her youngest apprentice ran past her and towards the cave. The girl was holding a handful of glowing green spheres the size of marbles she’d just picked up from the table. “Don’t worry, I’ll give them to Stefan and be right back!” she said before disappearing inside the cave.

“Franziska, come back right now!” Rosario tried to crawl inside the cave but couldn’t make it far. “Franziska!”

*****

The passage between the rocks was narrow and humid, covered in soft moss and small ferns, like the entrance to a fairy world. Franziska crawled effortlessly and didn’t have to go deep to be in what would have been complete darkness, only kept away thanks to the faint light emitted by the crystals braided into her hair. Holding onto the rope Stefan had tied to his belt, she kept going until she arrived at a wider space between the rocks where she could stand up.

Without natural light, the rocks were now dry and the air dusty. The light from the crystals in her hair wasn’t enough, and only then did Franziska remember the green beans she was trying to bring to Stefan. She took some out of her pocket and the boulders now looked coated in a witchy green light. Franziska oriented herself until she saw the rope going up to a small crevice between the rocks. She pushed herself upwards, crawled inside a short passage, and as soon as her head reached the opening, a bright light shone into her eyes, making her scream and cover her eyes. Her brother laughed, his voice echoing.

“Stefan, you idiot!”

It took him a moment to compose himself enough to speak. “You should have seen your face! Anyway, why did you follow me?”

“Because you forgot to pack the green beans.”

“Oh… right. Thanks for bringing them,” he said, reaching out. Franzi glared at him.

“You made me drop them! We have so few and I think they fell between the rocks…” she started searching for them but the little crystals were nowhere to be seen.

“Don’t worry about that, look!”

The girl looked up and instantly forgot what she was doing: before her was a large chamber that looked like a curved half cylinder, clearly the old road tunnel they were looking for. Between the remaining concrete walls, and the rocks and soil that had fallen through the partly collapsed walls, large roots pushed their way through. Attached to the roots were crystalline structures of all sizes, emitting luminescence of all tones and intensities. It was truly a fairy world, even if, to Franziska and her brother, this was hardly the first time they witnessed something like this.

“Pretty cool, right?” he untied the rope and fixed it to what looked like the window frame of a car door, now rusty and barely recognizable.

But Franziska didn’t register his words; she got out of the passage and stood in the middle of the tunnel, mesmerized. “Purple needles…” she pointed at some sharp conical crystals extending from a green root like thorns, “…and pink grapes.” She now stared at a cluster of translucent balls that looked quite similar to grapes; these in particular grew over thin and contorted violet roots. “And those are…!” she ran towards what looked like a yellow root with red specks; small, bright yellow crystals formed over it. “It’s pure yellow dust. Imagine all the fog bombs we could make with it!”

Stefan gave her a waxed paper bag from his backpack, and she then began carefully blowing at the yellow crystals so they would fall into the bag.

As his sister did this, Stefan collected from all the crystals he saw until he noticed a type of dark root he didn’t remember seeing before. It was almost pure black, and intense red polyhedral shapes accumulated on its surface. He walked closer, wondering about its uses.

The crystals that grew on the roots of behemoth trees all had uses to fend away monsters, but every type had to be processed differently and were only effective towards certain types of creatures. Purple needles were used to create solid weapons. Pink grapes were usually ground into a powder that evaporated into a thick fog that kept monsters at bay, just like what they’d used to create the defense circle around their camping site. The yellow dust Franziska collected was explosive when compressed and then hit with a certain force. And so on.

But the red crystals… what did they do?

Questions to save for later, he thought as he began stashing as many as possible inside his backpack. He was packing a large one that barely fit inside his bag, when his wristband brushed against something he thought was a different type of root. However, the touch with the crystals braided into his armband made it retract itself into the rocks.

“Franzi, we’re not alone!” he warned.

His sister instantly dropped the orange cluster she was holding. They gathered in the center of the tunnel, back to back.

“Do you think it’s a monster?”

“I think so. It reacted to the crystals on my armband.” He made a pause, but everything was quiet. “Dammit! We’re in a cave filled with crystals. How can there be a monster…?”

“Stefan… I don’t see any green crystals here.” She reached inside her pockets. “And I only have two green beans.”

She was right. There were none of the otherwise common green crystalline formations on the roots around them. This was bad. He took the two green pebbles from her and reached for his slingshot.

“W-what kind of monster does the green crystal keep away?” Franzi asked in a nervous voice.

His mind was racing. Knowing which monster was stalking them could be the difference between escaping or becoming another victim of the creatures that had been terrorizing the Earth for the past twenty years. He took a deep breath. The damp cave suddenly felt sinister. “Hey Franzi, how did that song go again?”

“What song?”

“The one Rosario made up.”

“The one you said was stupid?”

“Do you remember it or not?”

“Yeah! It goes…”

Forget the pink, be dead in a blink,

Have yellow and ink, and they won’t move an inch.

“It means the bark snakes. They’re fast and will bite your head off if you don’t have pink or at least yellow crystal.”

“I know, just keep going.”

“Um…”

If the monster crawls, gold is your aid.

Forget the brown, and a tail will knock you down.

If they fly and glide, keep purple and orange by your side.

But green is your only choice if they hang from upside down —

Stefan reacted in time, grabbed his sister by the arm, and jumped to a side. Rocks smashed onto the ground where they stood seconds before, as something that was hidden between the rocks above made itself free. In a swift decision, Stefan looked up, aimed, and fired at the gaping maw. The crystal broke in a flash of green light. A creature similar to a worm, with a mouth as only opening and large enough to eat him in one bite, recoiled and screeched. The movement caused more rocks to fall, blocking the children’s way out.

The Morsus inversus was a type of monstrous plant that stayed fixed to its anchor point, but that didn’t make it any less dangerous. After the Great Collapse, this monster originated from some vegetable species that propagated via modified subterranean stems, like asparagus or ginger.

To make things worse, the morsus that attacked them was a fully grown one, which meant its rhizomes could be around the entire tunnel, and others might have developed as well and were about to wake up.

As the thought crossed Stefan’s mind, pebbles and dust fell from the ceiling above and the concrete began to crack. The scent of freshly disturbed earth brought a flash of memories to his eyes: a cemetery, his sister crying, and a funeral without a priest.

Almost paralyzed by the panic, he took Franziska’s hand and both ran deeper into the cave. This had once been a road tunnel, which meant it had access from both sides; now they just hoped the other end wasn’t blocked.

*****