Neelix becomes interested in Earth history, spurring research about an ancestor of Captain Janeway named Shannon O'Donnell who was alive at the turn of the 21st century who she believed single-handedly fought to complete the Millenium Gate tower project at the turn of the 20th century, and would later be part of NASA's missions to Mars. Neelix, prompted by Janeway, proceeds to track down further information on Shannon.
Neelix (it wasn't Neelix who discovered this info, it was Seven Of Nine) discovers that Janeway's information was incorrect: Shannon was a traveler that happened to have her car break down in the small town where the Millennium gate was to be built. Set on December 27, 2000, the intent has caused most of the business in town to leave, save for a bookstore owned by Henry Janeway, who refuses to sell the store to make way for the project. Shannon joins Henry in the opposition, and learns that if Henry refuses to sell, the project would have to be moved to a new location. The two also develop a bond during this time. As it turns out, Shannon had been hired by the company to try to convince Henry to leave before the 11:59 deadline on New Year's Eve. When Henry discovers this, he asks her to leave, but as she drives away, she turns around, and trying another approach to convincing Henry to sell. He eventually relents at the very last minute, selling his bookstore to allow the tower to go forward.
When Janeway learns the truth about Shannon, who was never a NASA astronaut, she becomes despondent, as Shannon was her childhood hero to convince her to join Starfleet. However, Neelix has provided a surprise: a gathering of the senior crew to celebrate their ancestors, and presenting Janeway with a photograph of the elderly Shannon, after she had married Henry and raised their extended family together. Janeway realizes that the revelation about Shannon shouldn't impact what she's done with her own life.