After the events of the Hindenberg, and the trio's failure to ensure the crash and destruction, the future has changed. So much so that Lucy's sister now no longer exists, and Lucy's mother isn't dying of lung cancer.

When Flynn, the evildoer who stole the improved time machine, travels back to April 1865, Lucy, Wyatt, and Rufus head back to ensure that Lincoln is assassinated and the other three officials that John Wilkes Booth planned to kill stay alive.

Once there, they encounter a few problems. Flynn provided them with semi-automatic weapons, ruined the train so General Grant couldn't leave town and had to attend the play where Lincoln was murdered, and again attempted to persuade Lucy to join his cause as she supposedly will in the future of her own validity.

Unfortunately for Lucy, she begins to fall for Robert Todd Lincoln, and they change the future in drastic ways. Instead of Booth assassinating Lincoln, it was a tall man with an unknown weapon (Flynn). Again, history was changed and the consequences were inconsequential to the people in charge of their spontaneous trips to the past, even the disappearance of Lucy's sister Amy.