The Warning by James Patterson
Two roads lead to Mount Hope. None leads out.
Following a freak nuclear power-plant explosion, the small southern town was evacuated. Now, after a year in isolation, some residents are finally allowed to return home.
Best friends Maggie and Jordan quickly discover that Mount Hope is not as it was before. The roads leading out of town are blocked, phone networks and the Internet are cut off, and the power plant remains on military lockdown.
Something is horribly wrong, and their determination to uncover the truth soon has Maggie and Jordan in the crosshairs of a force more sinister than any they could have imagined.