Touted as the last true bastion of science and learning, the Commonwealth is the vast remnant of central eastern Massachusetts and home of the mysterious Institute, producer of incredibly lifelike androids. The Commonwealth is also home to the Railroad, an underground organization dedicated to freeing the androids from their Institute creators. Surrounding the fortified inner city, however, are hordes of failed experiments, new breeds of Super Mutants, and other, nameless horrors. The northern wastes were also the destination of the knowledgeable Doctor Madison Li, whose chemical expertise may soon be required...