The team travels back to the assassination of Lincoln to stop Flynn from making that night an even bigger tragedy.

A stunning turn during the American Revolution prompts Lucy, Wyatt, and Rufus to question whether they've been fighting on the wrong side this whole time. While Agent Christopher prepares for the worst back in present day, the team encounters the Father of the Country, makes a dubious pact, and confronts the possibility they may not be a trio for long.

After barely escaping an explosion at Mason Industries, Wyatt and Rufus chase the Mothership back to a French battlefront during World War 1 to rescue Lucy from Rittenhouse. There, they discover that Lucy has recruited Marie Curie, the famous French scientist and the only person ever to win two Nobel Prizes, to help save the life of a wounded American soldier, only to learn that the soldier is Lucy’s own great-grandfather who Rittenhouse is bringing to the present to be their leader.

When the Mothership jumps to South Carolina in 1863, the Time Team partners up with a courageous Union spy and military leader, Harriet Tubman - AKA "The General" - to thwart Rittenhouse's plan to alter the outcome of the Civil War. Back in the present, Rittenhouse hits the team where it hurts the most. Then, Jiya makes a daring escape from Rittenhouse that strands her in San Francisco's Chinatown in 1888 with no way home.