Already I was at a forty-five-degree angle and steepening as the bed groaned and juddered across the floor, leaving deep gouges in the hardwood. Someone’s not getting their deposit back, a surprisingly deep-seated part of my brain observed. I sprang up the steepening slope of mattress, toward the receding safety of the top of the bedroom-tube; but the bed crashed into some other piece of furniture and we jerked sideways, and I cried out and dived for the headboard as the angle approached vertical.

I was going to fall off, over the side, and there was nothing beneath me.

I cast around for something heavier to jump to, but nothing looked large enough to support my weight. I imagined tumbling into space gripping an end table, maybe a dozen pounds lighter as it tried to fall back up to its cylindrical floor. Which would be no consolation at all as I plunged into nothingness.

There was no time. I scrambled onto the pedestal of the headboard, itself beginning to slope as the bed slid around to the lower half of the curve. No time. I leapt for a bulky chest of drawers six feet away, arms grasping for handles, edges.

I smashed into it roughly and hugged its sides. But I was too heavy. I pulled away from the cylinder, dragging it with me off the curving wall of its ground, and we both started to fall.

I screamed in frustration and let it go, grabbing instead for the loose rope coiling by my head. The chest of drawers fell up, sickeningly, and hit the cylinder above with a splintering crash. An instant later I wrenched to a jerking stop, the rope burning through my fingers: I clenched with a death grip, tight enough to stop my fall.

I took a breath but it didn’t help.

I dangled twenty feet below the bed I was tied to, now dragged around to the bottom of the cylinder, gripping my rope at a point halfway up its length. Another twenty feet of slack curled beneath me. Below that was Elder Niko, swinging from the other end of the same rope, which in between us still looped around the lashed-together furniture above. He had come to a much rougher stop than me and was gasping, momentum swinging him in sickening arcs over the void beneath us.

I looked up at younger Niko, and immediately regretted it.

A free-standing doorframe stuck out of the cylinder, about two thirds of the way around the curve to the bottom. He must have grabbed the doorknob as he fell and twisted it, swinging the door open. Now he dangled from the knob of the open door, sideways and slanting down, and as I watched, a bracket holding it to the doorjamb groaned and twisted loose, only two bent screws still holding it in.

His hand was slipping on the knob. He looked down at me, frantic; looked over at the bed-and-armoire anchor his double and I were dangling from.

Gaging the distance.

And just as I opened my mouth to scream No!, he leapt for it.

Because the only reason Elder and I weren’t pulling our anchor down was that it outweighed us. The pull of the cylinder’s strange gravity overruled our downward tug, which was lighter.

But there was no way all three of us were lighter than that anchor. No way in hell.

He smashed into the armoire, shoving it sideways, and flailed for it. The bed jolted with it, its legs scraping across the cylinder above us with his momentum, but it didn’t stop. I watched in horror as the bed slid off the curve above us into empty space, then began to arc down, toward us, away from the floor above it.

We were starting to fall.

If it had been me, we’d all have died. I need time to consider a situation, to think things through. I don’t have split second reflexes.

Niko does.

He shot a glance behind him and kicked off the anchor, smashing into an overloaded and upside-down black bookshelf that I’m pretty sure was an IKEA Billy. He grabbed for a shelf but it pulled free, designed to resist only force pulling it down; books flew everywhere, but Niko’s grip flashed to the solid side of the bookshelf and he jerked roughly to a halt, tugging it across the hardwood above him, grumbling and shedding books like some beast made of library, sloughing its skin. But it stopped. It held. With all the books, it was heavier than him.

His weight now off it, the bed arced back up, pulling us with it.

But it hit the floor above our heads with disturbingly gentle force. We even bounced a foot or two back down before coming up to rest. My skin crawled as I realized what this meant: even without the weight of an extra Niko, we came horrifyingly close to outweighing our anchor.

The bed groaned, creaking, and one corner lifted again off the cylinder’s surface. I looked down. Elder Niko was climbing his rope, hand over hand. Murder in his eyes.

I leapt up mine, for a second sure I’d be faster. I had a head start. I was twenty years younger.

But my life hadn’t been given over to surviving down here, to stalking, to killing. And I’d forgotten I wasn’t at the end of my rope. Slack coiled beneath me. It gave me a head start, but also a leash, tied to my waist.

Elder reached the loop and hung his full weight on it.

I slipped four feet before my grip on the rope was firm enough to stop me, friction-burned hands screaming.

Below me, he laughed, and sprang up the rope like it was a ladder. My arm muscles were already aching. Before I could pull myself up more than a foot or two, his hand closed around my ankle.

I strained to pull away, kicking, and again felt the bed shift unsteadily above. I looked up. Younger Niko’s gaze met mine; he clung to the slanting bookcase, skiwampus, casting around wildly for a way to help, but there was nothing in reach. He couldn’t help me.

I looked down and saw the same face, shriveled in a blink by decades of rage into something monstrous.

“We don’t have to do this,” I panted, still trying to shake my leg free from his cold grasp. “We can all go through, get to the surface. Then go our separate ways. Like you said.”

“You fucking idiot.” With the hand not gripping me he fumbled at his belt. “You thought after all this time down here I’d forgive you? That we could be friends again like old times? No. You’re going to die. And then I’ll hunt that bitch down”—his eyes flashed up to his younger clone—“and kill him, again. First things first, though.” And he reached up with the knife he’d unclipped from his belt, flipped it open, and sawed into my calf.

I screamed, trying to pull away, but his other hand gripped my leg tight, and I looked up through the pain and starred vision at my Niko’s shocked, helpless, too-distant face, and below me his double laughed and kept sawing with terrible strength. In one fierce thrust he sawed through my jeans and into my skin, and drew the serrated blade back, cutting deeper, into flesh, into muscle.

“It’s your fault,” he grunted, and the strength drained from my hands as hot pain sliced through me. “I went looking for you. You know that? How I got lost.” My blood dribbled onto his face and he spat it away. “We had a fight. Don’t remember. What about.” He pulled the blade back and I screamed, trying to twist away, but he only gripped me more firmly. “But I remember hating you. I remember that. I remember hating you and deciding to go back anyway. If I hadn’t, if I’d turned around, I would have felt the sun again.” His breath was ragged. He shifted his grip on the knife. “But I went back. For you.” He sawed the blade deeper and I screamed and realized, then, that I couldn’t escape this, couldn’t escape him, that if I didn’t die from falling or bleeding out or being left for dead the best I could hope for would be a life down here in the dark, like him, left to wander forever, trapped, helpless, lost. Fighting it was impossible. It was already done and settled. Had been from the moment I set foot Downstairs, from the moment we saw the house, maybe even from the moment I’d first met him, first walked up to him and said hello because he was so fucking sexy and I thought I’d take a chance.

“He won’t forgive you, either.” He grimaced up at his younger self through teeth stained red by my blood. “He just hasn’t realized it yet.”

“He’s not you,” I gasped, “he’ll never be you.” And because I couldn’t make myself believe it I stomped down on his face as hard as I could.

He let out a whoof of air and something crunched as a splatter of blood arced out into darkness. His eyes rolled up into his head and he went limp, and then he fell. In thirty feet he reached the end of the rope around his waist and it jerked him to a horrible stop, flailing his limbs like a scarecrow. He dangled there, spread-eagled, face up, over the void. Unmoving.

Somewhere above me Niko was whooping in victory, but I barely heard him through the blood thumping in my ears, the high-pitched scream of pain in my leg. Refocusing my eyes, I dragged them down. The knife was still embedded in my calf. As if from a great distance, I reached with one hand, gripping the rope tight with the other, and pulled it free in a queasy sucking motion. Blood dribbled down my pant leg, dripping off my foot. Numbness and pain rippled through me, and muscles spasmed in my arm, but there was something I had to do before any other concerns. Woozy, I pressed the knife to the second rope, and started to saw.

“No, wait!” Niko shouted down at me. “The key! Do you have the key?”