For the first time in two years, Charlie had a free afternoon and unrestricted web access. Starting with links Mango sent, she read and watched videos on gene editing, scribbling notes, and struggled to finish anything because every topic threw up three more questions.

SNor had been a wake-up call to the world, but new infections had now dropped close to zero. The public had mostly decided they preferred not to dwell on something so depressing, but scientists realised it was the start of something much bigger.

Charlie read an article by a pessimistic virologist, who said that the ease of gene editing meant that some experimental accident or mad individual would wipe out the human population within fifty years. Others said simple hygiene procedures like hand-washing and UV sterilisation can make it very hard for viruses to spread, and there were optimists, pointing to the way that genetically modified tsetse flies had been used to eliminate malaria in parts of western Africa.

It remains a little-publicised fact that gene editing has already saved ten times more people from malarial deaths than were killed in the SNor outbreak.

Charlie read about governments panicking, banning all gene editing and forcing the registration of equipment and chemicals. Cynics said they’d have about as much success as governments had in their wars on drugs, and that it was more dangerous to have illegal underground labs than legal ones that could be monitored.

And while synthetic human viruses could be massively reduced with good hygiene, many scientists pointed out that viruses carried by birds, insects or rodents were much harder to control. Then there was the possibility of genetically altered bacteria, and a rumour that a Russian weapons lab had already developed a genetically modified fungus with reproductive spores that caused a severe allergic reaction and suffocated anyone that inhaled it.

Beyond the apocalyptic visions there were trashier stories too. Was a formerly pale TV star’s perfect olive skin the result of illegal gene therapy? Had the athlete who broke the hundred-metre sprint record at the last Olympics used gene therapy after a tendon injury? Then there was the eccentric Indonesian cult leader who’d cloned himself six times and claimed that one day each of his children would rule a continent.

‘I got your message,’ Brad said cheerfully, when he stuck his head into Charlie’s room, just after seven. ‘Glad you’re still with us.’

Charlie had been on her bed for three hours, and was surrounded by notes and the crumbs of three Radical Cake Collective muffins. Brad had done an after-school gym workout and wore black Nikes, and grey shorts. His T-shirt was balled up in his hand, and his torso glazed with sweat.

‘What you studying?’

‘Cake recipes,’ Charlie lied, gathering her notes and hoping Brad couldn’t see what was on them.