A solitary machine drives across the sun-drenched soil of the American West. A faint trail of dust lifts into the air as it moves along, scanning the landscape for signs of cognition. It's looking for a survivor to a human plague. It's looking for someone who can still think, someone whose mind was not wiped out by the disease. There are only a handful of places where a survivor might be. This machine, a sentinel, passes through the afflicted, looking for a spark. Looking for a light in the mental darkness at the dusk of mankind. But finding a survivor will only be one part of the journey.