Four years ago, when things start to fall apart out in NCR, Presper sent out his last team of scientists and grad students. Agnes, a fellow NCR scientist and frequent diplomat from the scientific community to the government, is the leader of the expedition. Using her skills and a "diplomatic immunity" pass she carried, she makes her way to Hoover Dam. Two days later, the NCR Congress building is destroyed, presumably in a conflict with the BOS.
The destruction of the congressional building is a severe upset to NCR and travel becomes difficult. Only by circuitous routes and careful display of her pass is Agnes' expedition able to reach Hoover Dam a year later.