It's Just the Gypsy in My Soul - S1.E7

A minor auto accident results in Louisa dreaming about Michael and herself as players in France in World War II, Michael as an R.A.F. pilot, and she as an American dancer. They fall in love as Michael tries to track down some V-2 rockets and Louisa is along for the ride. They entire cast is there, playing various roles in the story.