“Yes, I have the key. Do you want to go in?”

“Yes, please. That would be great, actually.”

Bellamy shot Clarke a questioning look, but she looked away, letting her mind wander in pursuit of a memory she wasn’t sure was ever hers to begin with.

Clarke forced herself to take a deep breath, just like she did before assisting Dr. Lahiri with a complicated surgical procedure. But this time, she wasn’t about to use a scalpel to expose someone’s tricuspid valve; she was bracing herself to enter the Exchange.

Clarke hated the vast hall that was always packed, no matter when you went. She hated haggling for a good price, and she really hated having to make small talk with the attendants, pretending like she cared whether a T-shirt was ten percent earth fibers or fifteen. But it was Wells’s birthday tomorrow, and Clarke was desperate to find him the perfect present.

Yet just when she had gathered the courage to step inside, Glass and Cora came her way, prompting Clarke to duck around the corner. There was no way she could pick a present for Wells with them watching, making loud comments about her selections as if she couldn’t hear them. She’d just have to come back later. They were scrutinizing scraps of fabrics with the same care Clarke reserved for tissue samples in the lab.

“I just don’t see any harm in looking.” A man’s voice drifted down the hall, making Clarke stop in her tracks.

“David, you know there won’t be anything even close to what we need at the Exchange. All that technology was snatched up years ago. We could check the black market on Walden, if you think it’s worth the risk.”

Clarke’s breath caught in her chest as she peeked around the corner. It was her parents. Clarke’s mother hadn’t gone to the Exchange in years, and she couldn’t remember her father ever going. What in the world were they doing here in the middle of the day, when they were supposed to be in their respective labs?

“The radio works,” her father was saying. “We just need to find a way to amplify the signal. It’ll be simple, really. We just need a few pieces of equipment.”

“Which is all well and good, except for the fact that there’s no one on the other end to hear us.”

“If anyone made it to Mount Weather, or to one of the CDC bunkers, then they have access to a radio. We just need to make sure—”

“Do you know how crazy you sound?” her mother said, lowering her voice. “The chances of it working are infinitesimally small.”

“But what if I’m not crazy? What if there are people down there, trying to make contact with us?” He fell quiet for a moment. “Don’t you want to let them know that they’re not alone?”

To their credit, Bellamy, Wells, and Sasha didn’t balk when Clarke told them about her parents and how she thought they might’ve known about the radio in Mount Weather. It was crazy, but no crazier than Bellamy and Wells discovering that they were brothers, or Clarke learning that her parents had been on Earth the entire time she’d been mourning their deaths.

Max unlocked the door with a loud click. The door creaked open on old hinges. He stepped aside and held out his arm, signaling for Clarke to enter. She took a hesitant step inside. It was small, no more than three or four people could fit comfortably, and one entire wall was covered with speakers, switches, and dials. The other three walls were hung with various instructional signs. Clarke’s eyes landed on a poster that showed various flags next to long strings of numbers. The labels read:

PARLIAMENT HILL, OTTAWA

CENTER FOR DISEASE CONTROL

10 DOWNING STREET, LONDON

PALACIO NACIONAL, MEXICO CITY

CIA

MI6

KANTEI, TOKYO

KREMLIN, MOSCOW

“When was the last time you tried to send out a signal?” Clarke asked.

“About a month ago,” Max said. “We’re due to try again in a couple of weeks. But honestly, we only do it as routine maintenance, mostly to make sure the equipment is still working. There’s never been so much as a blip, Clarke.”

“I know. But that doesn’t mean my parents weren’t onto something. Maybe being in here and using the same equipment they did will help me figure out where they went.”

“Well,” Max said, nodding, “I’ll leave you to it, then. Good luck.”

Clarke walked over to the controls, her hands trembling. To the right, a tall stack of equipment towered over the room. Cables and cords of every color and width poured out of it like tentacles. Clarke ran her hands over the machinery, too afraid to push any one thing. She studied the markings, combinations of letters and numbers she’d never seen before: kHz, km, GHZ, µm.

One switch seemed straightforward enough: It read ON/OFF. Clarke took a deep breath and flicked it up with a snap. She sucked in her breath as the whole apparatus lit up like it had been shocked to life. Lights flashed. Its guts seemed to whir and grind. Clicks and crackles emanated from somewhere deep inside. Then, a low, soft hiss filled the room, growing louder and steadier. It was mesmerizing—the sound of possible life out there, somewhere. Clarke could tell why her parents would have come here. They would have wanted to see for themselves, to hear the vastness of this planet with their own ears. To hear the sound of hope.

She spotted a small drawer under the console. She tugged it open and to her surprise found a small booklet. It was a manual. The pages crackled as she opened it and ran her finger down the instructions.

She could have spent all night in the radio room. She had no idea how much time passed while she pushed buttons, gently nudged dials a millimeter or two in one direction or another. And each time she made the slightest adjustment, the hiss changed, just a tiny bit. It was almost indiscernible, but Clarke could hear it. It was like the subtle distinction between the accent of a Phoenician and a Waldenite. And in each moment, she felt something she never dreamed she’d feel again—the presence of her parents. They had listened to this same endless sound. They had tweaked it and plumbed its depths for hints of a life outside Mount Weather. She just had to spend enough time here to figure out what they had discovered—and where it led them.