ZXR, a new muscle stimulant, is on trial for the general public. It was mainly invented as a cure for Multiple Sclerosis, but also an agent in new steroids and post-surgery medication to help strengthen patients. Something in the drug causes it to not only strengthen the muscles, but take over their general function. Eventually, it takes over all vital organs, including the brain, turning all patients into flesh-eating zombies.
This story follows the lives of the surviving population. A group of very different people, all simply trying to live through each day.