“Does it guess easy?” Mark hissed dramatically. “It must have a competition with us, my preciousss! If precious asks, and it doesn’t answer, we eats it, my precioussss. If it asks us, and we doesn’t answer, then we does what it wants, eh? We shows it the way out, yes!”

The rush of preparation for the storm had put the reading of The Hobbit on hold, but now there was nothing left to do except hope that the storm didn’t cause a landslide that buried the airlock. Considering how comparatively flat the slopes of Site Epsilon were, that wasn’t likely, so the five castaways sat next to Dragonfly’s cocoon, gathered around the single largest source of light in the cave, the computer in Mark’s hands. With the space suits deactivated, the only other light sources in the chamber were the indicators on the Amicitas life support box and the dim orange glow of the one active electric heater.

None of them had ever been in the cave after dark before. Oh, there had been the early exploration using space suit helmet lights, but even those had been during daytime outdoors. At night, without the suits, with only the bedrolls from Amicitas to separate them from the dirt floor, the cave was all shadows and gloom, right down to the constant trickling sound of the water heating system from Equestria running down into the well.

Spitfire could easily imagine Bilbo Baggins, a sort of human-pony, sitting next to an underground lake, facing the creepy, terrifying Gollum in the darkness and the horrible claustrophobic depths of the goblin cave, with nothing for light except the flickering light of a magic sword.

In fact, she could imagine it a little too easy. Indoors, under rock, at night was not a place most pegasi felt comfortable with, Spitfire even less than most.

“White horses?” she heard Starlight ask in a slightly offended tone. “White horses for teeth? Mark, are members of your species like beavers or something? Who has horse-sized teeth?”

“It’s a riddle, Starlight,” Cherry replied. “It’s not meant to be literal.”

“But... oh, never mind,” Starlight grumbled. “Just bear in mind I’m going to imagine the Royal Guard on parade every time I watch Mark eating from now on.”

“You watch me eat?” Mark asked. “Planning a nature documentary? ‘Here we see the Watney in his unnatural habitat, underground on a desert planet.’”

“What does ‘documentary’ mean? I know what a document is, but not a documentary.”

“It means I need to get back to reading the book. Then he asked his second: ‘Voiceless it cries, wingless flutters, toothless bites, mouthless mutters.’ What do you think that one is?”

Spitfire thought of the ten million stone teeth, most of them with pointed or jagged ends, all around them and above them. I think that one is a hint to pull the Harry Potter back out and read another quidditch game, she thought. I like quidditch. It’s played above a nice green field in open skies on a pleasant day. You don’t play quidditch in caves.

And nasty cannibal creatures don’t accost you in quidditch stadiums.

Well, hardly ever.

“Wind? Really? I’d never got that one!” Cherry said. “Hey, Spitfire, why didn’t you guess?”

“Huh?” Spitfire pulled her mind out of mental images of Gollum wearing a Slytherin scarf and returned her attention to the others. “Sorry, guess what?”

“The riddle,” Cherry said. “The answer was ‘wind’.”

“Oh. Hm.” She struggled to think. “Mark, read it me again, please.”

Mark read the riddle-poem again.

Spitfire shook her head. “I would not guess wind,” she said carefully. “The thing in the riddle is a monster. Evil. The wind is my friend. It doesn’t cry or bite. It whispers and… and… rubs?”

Mark and Starlight chuckled a bit. In Equestrian Starlight said, “A masseuse rubs, Spitfire. Is there something going on between you and the wind that you wouldn’t want the Canterlot Herald to know about?”

The pegasus snorted and turned her head, acting like she was ignoring the others as Mark recited something about eyes and faces. Again the others went into a frenzy of guessing, but of all people it was Fireball who guessed it- or almost; he said the sun looking at sunflowers, and the book said the sun on daisies. Feh. Sunflowers and daisies are totally different.

Then Mark read a new one, hissing his way through a truly sinister riddle: “… it lies behind stars and under hills, and empty holes it fills, it comes first and follows after, ends life, kills-“

Above them, something rumbled. Mark went silent, and everyone got just a little bit closer to one another.

“What was that?” Fireball asked. “Cave in?”

“Impossible,” Starlight said, her voice failing to sell the word with any conviction. “The roof is solid.”

“It’s thunder,” Spitfire said. “I never think I’d hear thunder on this planet.”

“It can’t be thunder,” Mark said. “We’d only hear thunder if the lightning were right on top-“

Blinding light filled the cave. A deafening CRACK struck the ears of the castaways like a whip. For half a second, a beam of sinuous light linked one of the crystals in the ceiling and The Stump. A smaller light lit up the far end of the farm, as the lightning traveled through the water heating system and grounded again in the metal-lined trench leading to the well.

Then there was a lesser crack, followed by the hissing sound of crystal fragments falling to the farmland below.

In the dim light of the computer screen, five faces looked at one another. Five bodies pressed against one another.

“Quartz is an insulator,” Mark muttered. “How can lightning get at us inside a cave made of quartz underground??”

“The sun crystals,” Starlight answered. “The enchantment channels light through. Light is a kind of electric magnetism. But the spell gathers up light, to make it brighter in the cave.”

“So it gather up lightning too,” Fireball grumbled. “Perfect.”

“Lightning went through pipes,” Spitfire added. “Did you see?”

“I think the life support system is insulated,” Starlight said. “Dragonfly would have known for sure.”

“It’s not safe here,” Cherry said. “Any ideas for someplace safer?

“Deeper into the cave?” Spitfire asked. “Keep to sides of cave?”

“We’d have to get too close to the runoff trench,” Mark pointed out.

More soft rumbling echoed in through the cave walls.

Cherry pointed up. “And too much under the-“

CRACK!

More crystals fell from the ceiling, hissing into the alfalfa.

Five castaways blinked the afterimages of the second lightning strike out of their eyes, huddling together in silence. All thought of leaving the comparative shelter of the cave entrance had vanished.

Finally Cherry said, “Or we could stay right here. I’m tired of reading for tonight. Can we watch TV? Electric Company maybe?”

Spitfire, grateful beyond words that she hadn’t been the one to say it first, nodded her head in perfect agreement.

Mark, without argument, closed the text window and brought up the video player, quickly replacing mental images of deep underground with actual images of bright colors and smiling faces.

Everyone watched, and listened, in silence.

Outside, Mars cried and bit and muttered with all the strength it could muster, setting off electrical auroras that popped and crackled through the dust-dense air.

Author's Notes:

Normal quartz is a very efficient insulator, except for piezoelectric effects.

But the lighting spell Starlight Glimmer used turned chunks of crystal on the hillside into active electromagnetic conduits. The spell normally passes along light and heat. Apparently it can also pass along a static electrical charge.

And once that charge is in the cave- a cave with Earth air pressure, Earth air mixture, and a considerable amount of humidity- a standard, if weak, lightning bolt is possible.

Especially when there's a large object about a meter high in an otherwise open area, surrounded by pipe buried just under the surface.

You still wouldn't want to get hit by it. It's weak only in comparison with its Earthly counterparts.

And I think Spitfire is right: when you're in a cave with only one exit, sitting out a night wondering if you'll survive, is not a good time to get introduced to Gollum.