Verne and Marty McFly took the DeLorean time machine to September 27, 1944 to retrieve the blueprints. Their plan was foiled, however, when the civil defense warden caught them trying to break into Doc's apartment, and impounded the DeLorean.
Without a way home, Verne and Marty spent the night at a victory garden in Courthouse Square. Marty accidentally enlisted in the United States Army, while Verne met Dorothy as a young girl. Verne found he actually enjoyed dancing, and entered a contest at a USO show with Dorothy to distract Sergeant Frank Tannen, who was chasing Marty for going AWOL.
Dorothy and Verne won a trophy for dancing the jitterbug, successfully allowing Marty to escape. That night, Marty and Verne sneaked past the guards to take back the DeLorean, and headed back to 1991. In this new timeline, Dorothy is the proud owner of a dancing trophy — a feat she never managed to accomplish before.