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.
The Time Team chases Rittenhouse to a stock car race in the 1950s where Wyatt learns that his favorite race car driver is actually a Rittenhouse sleeper agent on a mission to destroy the American car industry. To stop the Rittenhouse plan, Wyatt, Lucy and Rufus team up with Wendell Scott, the first African-American NASCAR driver.
When a Rittenhouse sleeper agent in 1941 Hollywood steals the only copy of Citizen Kane, Lucy, Wyatt and Rufus team up with Hedy Lamarr to get it back. Hedy Lamarr turns out to be not only a glamorous movie star but also a scientific wizard whose discoveries led to the invention of Wi-Fi.
While Wyatt sneaks away from the bunker to face an unbelievable truth, Lucy, Rufus and their former enemy-turned- teammate, Garcia Flynn, chase the Mothership to the Salem Witch Trials. There they must prevent the execution of a headstrong young woman who, it turns out, is mother to one of the most consequential Americans of all time.
When a mission goes awry, Wyatt and Rufus are forced to bring a 17-year-old John F. Kennedy with them to the present. Anxious to return the future president to history, the team must find a way to work together to rescue JFK and return him to the past before Rittenhouse assassinates him in 2018.
When Rufus and Jiya add a fourth seat to the Lifeboat, for the first time ever, Connor Mason joins the team as they travel back to the dusty backroads and smoky juke joints of the Depression-era South to rescue the life and legacy of Robert Johnson - King of the Delta Blues, Godfather of Rock n' Roll and a man who, legend has it, bought his musical genius from the Devil for the price of his soul. Meanwhile, Agent Christopher keeps Wyatt in the present to execute a dangerous raid on Rittenhouse headquarters.
In the bustle of 1919 New York City, suffragette Alice Paul is framed for murder and the Time Team partners up with legendary female crime solver Grace Humiston - AKA "Mrs. Sherlock Holmes". Together they attempt to prove Alice's innocence in time for her to give a powerful speech that turns the tide in the passage of the 19th Amendment giving women the right to vote. Back in the present, Connor Mason salvages key intel from the Rittenhouse raid.
The Time Team travels back to 1981 Washington D.C. on the day President Reagan was shot, only to discover that the Sleeper's target isn't the President - but a young rookie police officer.
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.
When Jiya makes a daring escape from Rittenhouse that strands her in San Francisco's Chinatown in 1888 with no way home, the fractured Time Team goes back to save her.