They followed the main east-west highway across Bana to Guaqua, once marking the end of an old-time tramcar line, once a market village, once a university town. Bana’s main roads still had streetlights and their yellow glow fell onto the ground in triangles. Guaqua was a hodgepodge of broken buildings along the ridge of the Ama River valley, outside the Immersion Zone. A few people walked the lanes and streets, looking for any kind of place with a roof. No one spoke; everyone held their destination close. The evacuation announcements had stopped.

“Did this town have a square?” Sorrel whispered to Bibi, trying to make sense of the mounds of rubble and shattered sidewalks.

“Yes, kind of. Not really a square. But after one of the rain bombs, the Domins piled up all the wreckage in the middle. Over there.” Bibi nodded at a dark, irregular mountain of debris, more in shadow than light. “The river used to be behind those buildings, way down. I went there once… when it was a river.”

The streetlights revealed the roofless, windowless buildings, but the slope behind them was in total darkness and that was where they had to go.

Bibi went behind a crumbling wall between two buildings and pulled out the PlAK. They had to be sparing with its use until they could use the solar charger. “There was a message from Sesame,” she said, “but read it when we stop. Look. I think the aqueduct is down there.” She pointed. The cracked road was edged by slabs of sidewalk, uplifted and moved sideways.

“I can’t see anything. Can you? Can we really get down there?” Sorrel asked.

“We’ll have to. Look, there’s a house over there with some light inside. Maybe we can see better over there.” Further up the road, Sorrel saw light flickering through windows in a standing wall. “No roof,” she said. “You can’t call that a house.”

“People are inside, though.”

They walked closer and Sorrel heard low voices. A child cried and a woman’s voice shushed and sang an old lullaby. Maybe they were resting, but it was unlikely – travellers had to use every hour of the night to search. How could they survive without a roof? The shadows thrown by the walls would move around – would the people have to stand or lie in them, hiding from the sun?

Her mother touched her arm. “Come on.”

They scrambled around the side of the house and stood at the top of the black slope. Bibi shone the small PlAK light at the immense darkness of the river valley.

“Use the searchlight function,” Sorrel said.

Bibi shook her head. “Uses too much power.”