Six weeks after the explosion in Mason Industries, the presumed dead Wyatt, Rufus, Jiya, and Connor are trying to make the Lifeboat to work again in order to find and save Lucy, even though some of them think she is dead, while Denise is keeping them hidden in a decommissioned nuclear bunker.
When the Lifeboat is ready, they find out that the Mothership is in France on September 18th, 1918, where Wyatt and Rufus are ready to travel to find Lucy.
Meanwhile, Lucy, her mother Carol and Emma are trying to save a man, Nicholas Keens, who wrote a manifesto 100 years ago, of how to change the world if you change history.
Wyatt and Rufus find out an iPhone in a soldier with the manifesto, and later they rescue Lucy from Carol and Emma.
When they return back they figure out that the Mothership and Rittenhouse have sent agents back in history and they are waiting for the moment to act.