In less than ten minutes, all but one person standing inside the red circle will be dead.

We take bets on who.

"It's ten to one on the new fighter," I whispered to Xyla, checking over my shoulder to make sure the K-guards hadn't moved. "Think he's worth my last coin?" The dim light of the screens painted everyone a somber gray, but Xyla's hair gleamed bone white. We sat hip to hip, squeezed onto one of the grimy benches that faced the screens.

"I'd pay our last coin to spend a night with him," Xyla said, her grin matching mine.

"What about Wesson?"

Xyla winked. "I don't have to pay to spend a night with him."

My snorts of laughter earned us a few dirty looks before I managed to turn them into the more acceptable Belly cough. In the low lights of the filthy cafeteria, surrounded by X and Y engineers coated in soot and smoke, there was precious little to laugh at.

Xyla always told me I was beautiful, like the panther in her favorite novel The Jungle Book; deep eyes, inky black hair and lithe sulking power. To which I rolled my eyes. No one even noticed me when Xyla was near. White-blond hair, blazing blue eyes, taller and stronger than many of the men. If the handsome fighter had come down here, he would have been terrified or mesmerized by her—maybe both. Still, I was thankful that I was the one who blended into the shadows.

As a Z, my life depended on it.

Across a room of long tables filled with hundreds of X and Y engineers, Yerik, a bald engineer with a bulbous nose, was running a steaming business. These few minutes before the Letter Trial started, the betting ran the strongest. Yerik winked at me from across the room, and I nodded back, a twist of jealousy in my gut that I couldn't host the bets myself.

Silent K-guards stood at the edges of the room, their black uniforms the darkest shadows in the otherwise metal room made to hold some 600 engineers—just one of the many cafeterias in the vast, smog-filled metal underworld of the Belly. I liked to think the K-guards didn't know about the betting, that we'd pulled one over on them, but we were careful either way.

The buzz of the room silenced as each of the five screens on the furthest wall merged to show the newest trial combatant. He was tall, with golden-hued skin and wide, strong shoulders. Even so he looked barely older than me. His youth set him apart almost as much as his clean skin, full body, and lustrous hair—all of which marked him as from a higher letter than the Belly. Whatever he'd done, it was bad enough they'd sent him to the final Letter Trial. He could win, and move up. But even if you won the bottom Letter Trial, you still had to face four other Letter Trials before being given a new letter and a new life. I'd once asked Yaneli if anyone had ever made it to the Top from the Belly. She laughed.

"What do you think he did?" I whispered to Xyla, unable to take my eyes off the screen, until they panned to the next fighter, a middle-aged man with a heavy gut and ugly sneer.

"With that body and face, probably caught the eye of the wrong wife." Xyla shrugged. "He's a bad bet, don't waste your money on him."

I rolled my last coin over the flesh fingers on my right hand, and then the metal fingers on my left, where the coin made a soft clink-clink-clink. Yaneli liked to call Xyla and me "the blind leading the blind." But there was something about this new, young fighter, and the hate in his eyes. Like he'd lost everything he loved, and all that was left was to watch the world burn.

I knew that look.

"Twenty on the new one," I declared, and slid the heavy brass coin down the table, the slight zing just audible over the low conversations. My pulse raced, a high rolling through me. Across the dented and dirty cafeteria tables Yerik winked and, when it reached him, slid my coin into a fattening pouch.

Wesson, Xyla's current broad-shouldered paramour, caught my eye and gave me a wistful smile, as if hoping that I would scoot over and give him a spot next to Xyla. Fat chance. Something about Wesson's sunny demeanor annoyed me. Nobody was that happy all the time—even if they were dating Xyla. Especially if they're dating Xyla.

Beside me, Xyla lifted her tin cup full of her daily water ration. Or, at least, her official water ration—the rest of the water we needed we stole straight from the pipes. "When we win, we fill these suckers up with wine," she declared.

"Wine? I'm thinking whisky." We clinked the cups together and drank deeply, slamming them back to the table at the same moment. This time no one bothered to chastise us. Tense, whispered conversations grew across the room as the time drew closer. Besides the huge screens before that would show the fight, the only other light came from the information monitors screwed in place on the walls, shining with whatever message the Top wanted us to read today. Xyla and I once tried to steal one, but it had some kind of internal alarm. A shame really, because even though they usually only carried annoying messages—Your Admiral loves you! Be the Best Letter You Can be!—sometimes they showed a picture of a moving ocean, or a forest, like the screens were a window to Old Earth itself. And I would have given all the money in the galaxy for a true glimpse of any Earth, old or new.

Xyla and I had a good spot today, right up front, so the nearest guard couldn't get to us without walking around one of the long dining hall tables first. Also nice because the table was so crowded Wesson couldn't join us. No X's, Y's, women or children were fighting today, so the mood was lighter, voices a low murmur instead of a charged silence. Watching higher levels fight, it was easier to tell yourself that whatever they'd done, they deserved it. There was no one in the Beast lower than the X and Y's.

Except for me, of course.