All of the best ideas we’ve ever had have also seemed like the most obvious ones afterwards. And the plastic-bag rope was one of those. Looking back on it now, it seems weird we hadn’t thought about tying them together before, but we honestly hadn’t. You get loads, hundreds maybe, of plastic bags floating around you on the sea each day. We used them for lots of things: sleeping bags (with other bags stuffed inside as padding); fashion accessories (when twisted together and looped into necklaces or colourful belts); raincoats; clothing; for sitting on when you just couldn’t stand the feel of that gloopy mesoglea beneath you; or even just for burning. But a rope was something we’d never made before. The possibilities seemed endless.

‘Zip wire, I think it was called?’ said Kate. ‘I remember it from Before; it was in a park just for children to play in. It was so much fun! You’d get on at one end, and then sort of slide along the rope to the other end really quickly. It would pull you along.’

‘How would it pull you along, though?’ said Lana. ‘Because we’ve not had much success making anything mechanical out of shredded plastic bags and seaweed. If we could do that, we’d have built a flippin’ aeroplane and got us off this thing ages ago.’

‘It might have been called a Flying Fox?’ said Kate, with a frown. ‘No, it can’t have been. That’s a silly name. I don’t know how it would pull you along. But we could attach the rope at this end, and just climb along it. We wouldn’t have to slide along.’

‘What would we attach the other end to?’ said Lana. ‘Where would we be sliding to?’

‘The boat,’ said Kate. ‘When we get it here, we could tie the end of the rope to it and then push the boat away. Then when it got past the tentacles we could climb along the rope and swim to shore.’

‘That sounds crap,’ said Lana. But she said it more out of habit than conviction. We’d tried much stupider ideas before.

‘I need another load of bags,’ said James, calling over to the Big House. ‘Oi! John, have we got any more bags coming?’ John gave him a wave. Half the people on board were working on our project by now, and the Big House was full of people ripping apart the elaborate plastic-bag wallpaper inside. ‘What do you think that wave means?’

‘It means he’s sorting it out, James,’ I said. ‘He’s not the sort of man to wave just to say hello, is he? Look, we’ve all pretty much finished. Shall we join our ropes together to make one long one?’

We laid our ropes out on the surface.

‘They’re a bit thin, aren’t they?’ said Lana.