The War to End All Wars

S2 E1: In the Season 2 premiere, after barely escaping an explosion at Mason Industries, Wyatt and Rufus chase the Mothership back to a French battlefront during World War One to rescue Lucy from Rittenhouse. There, they discover that Lucy has recruited Marie Curie, the famous French scientist, 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.