In 2039 the Indomitable landed on the grounds of UCLA as part of the Roxolan invasion fleet. After its troops deployed and attacked, most were killed or wounded and the rest captured by United States Army troops.
Liz, a UCLA student in the home timeline, was the one who went with her parents to the devastated timeline and had the task of actually going to the alternate UCLA library and scanning historical information to further this research project. She eventually came up with the crucial piece of information about Vyacheslav Molotov having had a different position in the Soviet hierarchy of this timeline than he had in the history of the Home timeline.
However, Liz's interest in the UCLA library also made Valley soldier Dan, who was in love with her, question her motives and suspect her of being a spy. The explosive final confrontation between Liz and Dan, which nearly caused Liz's arrest and which did lead to Dan's discovering the crosstime secret, happened on the UCLA campus after she left the library.
Having had a chance to see the UCLA campus on both timelines and make comparisons, Liz was greatly saddened and depressed to see its decrepit condition in the nuclear-devastated timeline.