Paris, 1895. Glamour hides a city on the brink. One morning, a young woman boards the Granville Express with a deadly plan. On the journey lives intertwine in explosive ways. There are the railway crew who have everything to lose, a little boy travelling alone for the first time, an elderly statesman with his fragile wife and a lonely artist far from home. The train speeds towards the City of Light and into a future that will change everything . . .