Timeless tells the story of a mysterious criminal who steals a secret state-of-the-art time machine, intent on destroying America as we know it by changing the past. The only hope is an unexpected team: a scientist, a soldier and a history professor, who must use the machine's prototype to travel back in time to critical events. While they must make every effort not to affect the past themselves, they must also stay one step ahead of this dangerous fugitive. But can this handpicked team uncover the mystery behind it all and end his destruction before it's too late?
The team tracks the Mothership to South Carolina, 1955, and realizes that Rittenhouse plans to sabotage the stock car race there. Meanwhile, Carol oversees Nicholas' introduction to 2018, and Lucy and Wyatt end up in close quarters.
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 – the yet to be born Benjamin Franklin. When Lucy is accused of being a witch, the team rallies together not only to save Abiah and Lucy, but all the accused women.
When a mission goes awry, Wyatt and Rufus are forced to bring a 17-year-old John F. Kennedy with them to the present. But while the Lifeboat is recharging for the return trip, Kennedy escapes from the bunker… into modern day San Francisco. 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.