Following "The Inside", Nichols found work on the fifth season of the serial action series "Alias" in 2005, being cast that July. Nichols starred as Rachel Gibson, a computer expert who thought she was working for the CIA when in fact she was working for a dangerous criminal organization—a situation similar to that of the series' main character Sydney Bristow (Jennifer Garner) in the first season. Discovering the truth, Gibson joins the real CIA and becomes Bristow's protégée. Of working on "Alias", Nichols said that "to say it's the nicest set on the planet is an understatement". Her role involved multiple fight sequences, as did Garner's. Nichols worked with Garner's personal trainer; she said she "already knew that [Garner's] job was extremely hard. But I didn't know how difficult it was until I started training for just one fight." Nichols was being groomed to replace Garner as the main character due to the latter's pregnancy, which had been written into the storyline. But "Alias" was canceled in November 2005, making its fifth season its final. "I think everybody knew that the show wouldn't work without Jennifer", Nichols said, "But still, they were grooming me, so it was heartbreaking when it happened."