"There is an expression in the Wasteland: "Old World Blues". It refers to those so obsessed with the past they can't see the present, even less the future, for what it is."
"The residents of the Mojave have long assumed the trackless wastes of the ‘Big Mountain' are a no-mans' land, a desolate stretch where no living thing can survive. In Old World Blues, you discover that it is anything but..."
In Old World Blues, the Courier discovers how some of the Mojave’s mutated monsters (cazadores and night stalkers) came into being while unwittingly becoming a lab rat in a science experiment gone awry. The Courier must scour the pre-War research centers of Big Mountain in search of technology that can either turn the tables on your kidnappers or help them fight against an even greater threat.
After being transported to the Big MT research crater, you find that you're the only hope of saving the "Think Tank" – a strange group of post-human researchers who inhabit the facility. They enlist your aid to save them from their own experiments - experiments that have gone horribly out of control. As you explore the Big Mountain crater and its many underground labs, you’ll confront strange mutated animals, battle terrifying new atomic robots and discover a new home base to call your own. Recover all the weapons, armor and tech of the pre-War era and use them to help save all of Science, and eventually find your own brain which has been removed from you as well as your spine and heart.