The sun is a glowing ball seen through the storm wall, casting wavering shadows across the ice. Stepping out of the cave, Hallon feels like she’s walking on the ocean, the tides constantly shifting under her feet. She holds onto Milo’s arm to make sure he doesn’t fall. It’s a good thing too, because Milo’s knees nearly give out when he sees the wall.

“That’s impossible,” he says in a whisper. “I know I’m supposed to be insane, but I didn’t think I was this imaginative.”

“You’re not insane,” Hallon says.

“I have to be. With all that’s happened—the explosion and the giant and the running and being shot—I was shot!—and here I am now with the most beautiful girl I’ve ever met and not feeling like I’ve been shot, looking at a meteorological phenomena that’s impossible. What other explanation is there than I’ve gone completely around the bend?”

“Well, when you put it like that, it does seem a bit far fetched.”

“A bit? A bit?” There’s hysteria in Milo’s voice.

And Hallon can’t blame him for it. One moment he was safe at home tinkering with his invention, and the next, kidnapped and taken to a world he doesn’t understand. The situation was bound to affect him. She’s just lucky it was delayed this long.

“Milo, you’re a doctor of physics.”

He blinks, trying to follow the turn in conversation. “Yes.”

“In everything you’ve studied, is there a chance—any chance at all—for parallel universes to exist?” Hallon watches to see how he answers.

“No. Yes. It may be possible if you extend Applegate’s Outer Thesis to its natural conclusions, but—” He shakes his head. “You haven’t read Applegate, so you’ll have to trust me when I tell you that no one takes him seriously. He’s a loon.”

“This Outer Thesis was proved wrong?”

“No,” Milo says, “but it’s only a matter of time.”

Hallon takes a breath. “Then consider this. Throughout history, there were ideas that at first seemed impossible because they didn’t fit within people’s conceptions of reality, but in time were proved right.”

“Like Galileo’s work,” Milo says.

“Yes, exactly. Like Galileo. Such an interesting man. If it wasn’t for Urban… But never mind, that’s beside the point. The point is that the truth, both scientific and otherwise, is constantly unfolding. But it needs an open mind. Without that, the truth would be locked away behind old ideas held by old men.” Hallon points to the storm wall. “That’s impossible based on what you know, but what about what you don’t know? In this universe, the laws of physics and chemistry may be different than back home. Those differences could be what makes the wall possible. The reason it feels impossible is because you don’t know the underlying science. Not yet anyway.”

“I suppose,” Milo says, “but the probabilities would be minuscule.”

“A slim chance is better than none,” Hallon says. “Just think about it. That’s all I ask.”

Milo looks towards the storm wall. “All right. I will. I remember what you said before. That we can affect our experiences and we might as well work towards making them better.”

“That’s the spirit.” Hallon smiles to encourage him, and Milo takes heart from it.

His smile in return is endearingly lopsided. “Do we know where we’re going?”

“As a matter of fact, we do,” Hallon says. “East.”

“Because?” Milo asks.

“Well, there’s a reason,” Hallon says. “I promise you there is, but I don’t think you’re ready to hear it. Will you trust me for now?”

Milo nods, suddenly shy. “I do.”

“Great. Wonderful. Then we’d better get started. I want to take advantage of these shadows while we have them. They’ll camouflage us from anyone looking.”

“Okay,” Milo says, “and I’ll think about what you said while we walk. Don’t mind it if I… ah… mutter.”

“I won’t,” Hallon says.

True to his word, Milo mutters as he walks. To Hallon’s ears, it sounds like he’s moving through the syllabus of an increasingly thorough physics course, with Milo testing each principle and deciding whether it’s valid or not on this world. Given the amount of math involved, he’ll be at it for a good long time. She doesn’t mind though. If that’s what the boy needs to stay sane, then that’s what he needs. Besides, Hallon has her own work to do.

She joins with Eratosthenes to plan their route through the mountains. They look for the easiest terrain to traverse, for paths that avoid the soldiers’ patrols, for places to rest along the way. The route they pick out will add miles to the journey, but it’s better than being shot.

Milo’s injuries force them to move slowly, and sooner than she’d like, he’s panting. His eyes struggle to stay open. They’re still hours from sunset, but they have to stop. Eratosthenes finds them a gap in the ice, a crevasse three feet wide that slides down to a shallow bowl.

“Can you manage the way down?” Hallon asks.

Milo just nods. It’s all he can do after half a day walking on the ice. It’s a wonder he’s been able to come this far.

Hallon slides down, and Milo follows after with a grunt. She has him sit on her coat while she examines his wound. The bandages are a rusty red, but there’s no new blood and still no pus. His forehead is hot but from exhaustion, not fever. The spells inside him continue to do their work. All is as well as can be, and what Milo needs most right now is sleep.

He’s snoring in moments. It’s a handy trick that every soldier learns eventually—to be able to sleep anywhere and anywhen—because you never know when you’ll get your next chance. She wraps herself around his back and opens the Gate of the Sun Horse. Fire flows through her, demanding that she run and jump and fight, but she lets it pool instead. The heat builds and builds until the sweat on her brow steams and she’s sure there’s enough heat radiating to keep Milo warm. While he sleeps, she keeps vigil through the rest of the day and night. Letting the fire go untended is never a good idea.

The next day, Milo wakes up when she untangles herself from him. His face turns red from blushing. Exhausted as she is, Hallon still has energy enough to be amused. “How do you feel?”

“All—” There’s a catch in Milo’s throat. “All right. Hungry. Tired.”

“There’s no food, but if you melt snow in your mouth, it’ll help.”

“I know. I will.” Milo looks around their shelter as if seeing it for the first time.

“Here, let me help you up.”

“No,” Milo says. “I—ah, I can do it myself. Let me just get my bearings.”

“Fair enough,” Hallon says and leaves him to it.

The way back up has enough irregularities that it shouldn’t be too difficult to climb. Milo joins her when he’s ready, and she helps pull him back up to the ice. His wounds are healing at an incredible rate thanks to Hallon’s spells. He’s hungry though. Hallon can tell from his eyes, and she draws on the fire to feed them both with its energy. There’ll be a price to pay later of course. She imagines she’ll sleep for a week. Maybe two.

Their route takes them steadily east around the factories and then southeast towards the pipeline. With every step, the storm wall looms larger, dwarfing the mountain range it straddles. Lightning flashes, and the trapped wind beats at the boundary in despair. They hear their destination before they see it—a strange and terrible clamor that turns out to be the tunnel’s entrance. The wall doesn’t stop the storm’s howling rage from being heard through the rock.

At a hundred feet tall and a hundred-fifty feet wide, the tunnel is an engineering marvel but insignificant in comparison to the storm above it. Standing alongside the pipeline, Hallon can hear the whoosh of a river’s worth of water inside.

Milo’s stares at the entrance. “There are no lights.”

Hallon nods. “There’s not much traffic going through, so they’re not necessary. Anyone working inside probably brings their own light with them. We’d best keep a hand on the tunnel wall to make sure we don’t stumble.”

“There are no lights,” he says again. Milo’s kept calm given all that’s happened, but the tunnel has him shaken. “I’m... ah… not very good with the dark. In fact, I’m deathly afraid of dark, underground places.”

“We have to keep going. If we stay here, we’ll starve.”

Milo smiles weakly. “My mind understands, but my legs won’t move.”

“All right,” Hallon says. “I’ll help if you let me. Will you? Let me?”

He nods. “I don’t know what else to do.”

“This fear,” she says, weaving her spirit into the words, gathering the energy into her hands. “It served you once, but no longer. In this place, in this moment, this fear hinders the necessities of your being.” Hallon synchronizes her breathing with his. She lets the words ripple through him. A dark gray marble, streaked black, begins to form in the palm of her hand. “So, I will guard this fear for you. It is yours, and I will not take it away, but only hold it in safekeeping until the time it is necessary to return it to you.”

She closes her hand around the marble, and Milo’s breathing eases. His eyes clear.

“Oh.”

“Better?” Hallon asks.

Milo licks his lips. “Yes.”

“Good. Now we’ll walk.”

The air inside is close and muggy, smelling of old stone, steel, and mildew. The maelstrom roars and shrieks, the walls vibrating with the violence above them. Rock dust falls onto Hallon’s head. Her ears ring. She feels like she’s inside a drum, one that’s being beaten by a gaggle of determined children. Never has a journey felt so long.