Damen squeezed his brother's shoulder with his great mat of a hand. "You just work at getting healthy." He stood straight and walked to the teepee flap. "I'm sorry to be so tough, little brother," he said awkwardly, "but it's for your own good." He pulled the flap closed behind him.

Allel cackled sardonically. "Now, where have I heard that before? People always mean so well... but we go nowhere, while the ice closes all around us."

Teal lay back and stared at the darkness beyond the teepee's chimney flue. "So that's it. Damen will never let me out of here." A despair as complete as the world's roof settled over him. "It's over, then."

"Not necessarily." Allel's voice was muffled.

Teal turned -- and then began struggling off the pallet. "Grandmother, what have you done?"

The stone knife lay on the mat, streaked with blood. A great gash opened Allel's face from temple to throat. The old woman swayed slightly, blood pooling around her neck. "Take the knife," she said hoarsely. "I'll say it was you."

"But..."

"In my mother's day, they'd have killed you for this, you know? But now, as times have grown harsher, we've had to work out laws to control each other. So they'll be civilized... They'll exile you. Just like Damen said. You can go where you want."

"But--"

"No buts. I'll make sure Erwal is cared for." She slumped forward. "Take the knife," she whispered. "Do it."

Involuntarily, she cried out. Blood looped over her mouth.

Outside the teepee there were running footsteps, lamps, shouts. Teal struggled across the mat and put his arm around the thin shoulders...

...and grasped the knife.

They let him recover from his balloon fall. They gave him a suit of quilted leather, containers for water, flints, a coil of rope... they didn't want to think they were sending him to his death.

Although, of course, that was exactly what they were doing.

On his last night Erwal came to his guarded teepee. She pressed a bundle wrapped in skin into his hands -- and then spat in his face, and hurried away.

Teal was twenty years old. He felt something soft dying inside him.

Inside the skin was his grandmother's knife, cleaned of blood. Teal tucked it into his belt and tried to sleep.

At dawn, most of the village turned out to watch him leave. Teal stared at the slack faces, the children with limbs like twigs, and beyond them the huddle of shabby little teepees, the piles of lichen, a half-butchered mummy-cow carcass. Once, he thought, we could build worlds. We even built this boxworld. Now: now, look at us.

There was no sign of Damen, or Erwal, or Allel.

Teal turned away, pulling his hood closed against the cold.

His feet were already aching by the time he passed the bridge anchor. There'd been no will to rebuild the world-bridge, and the rope lay crumpled amid the frost.