In the future, most of humanity has been infected by a variation of a fungus known as the Ophiocordyceps unilateralis. The infected, referred to as "hungries", quickly lose their mental powers and feed on the flesh of healthy humans. The disease spreads through blood and saliva, but can also spread through spores created by the fungus, which needs an unknown trigger to be opened. The few surviving members of the human race either live in heavily-guarded areas (such as the Beacon) or else roam in packs living off the land. The latter are called junkers.