My weird plot line: Time : near future A virus is developed and sold secretly that can be deployed to other devices subtlely via Bluetooth. The affected device suddenly begins overheating and catches fire within a minute. The person responsible for developing and spreading the virus is actually a group of people. They move about in society unnoticed, deploying the virus at will. No one knows how many people are in the group. The public is scared because of the random damages to their phones and danger caused by having phones in public. Phones are banned for public safety. Mesh networks and pay phones are the only distance communication available outside the home. The virus is actually a solvable equation although it requires an almost infinite computational resources to solve. Something involving a number like tree3.