The key to the mystery
Limpley Stoke is a mysterious town in England, in the Real World. The reason it is so mysterious is that, wherever you go in the area around it, you will find signs informing you that there is no access to Limpley Stoke. From anywhere. Nothing goes in or out of Limpley Stoke, ever. It almost sounds like a plothole. In fact, further information suggests that it is caused by the Avon Rift.
Investigation[]
Agent Morgan left on a month-long trip to investigate Limpley Stoke immediately prior to the Macrovirus Epidemic. More details of her findings are available here.