"I don't mean in general," says Bina, trying not to lean too heavily on Twelve. The noise is incredible, larger thumps and bangs almost lost in deep omnipresent roar. It sounds how Bina imagines putting your head in front of a sand-blaster might feel. They are having to shout very loud to be heard. "I mean here. If she gets above us, she can climb up all the loops like a ladder and make it to tomorrow."

When this fails to get the reaction she expects, Bina looks up and finds Twelve not looking at her, but at the sky.

"Duck!" yells Twelve right in her ear.

"What?" Bina starts to ask, but Twelve shoves her out of the way.