Only ten percent of American born mutants live to see their twentieth birthday. Some are attacked by frightened neighborhood mobs, many murdered in confrontations with other mutants, but most have been executed by the U.S. Government's homo-superior extermination androids: the Sentinels. Throughout America, desperate and fearful mutants have banded together in small groups, living under the streets of our largest cities where they remain hidden from sentinel detection. They do not want to be heroes or villains, they only hope to survive.