In Cornwall in 1815, Demelza sees a horseman riding down the valley and senses disruption to the domestic contentment she has fought so hard to achieve. Ross has little option but to accept the summons—and travel to Paris with his family, as an "observer" of the French armed forces. Parisian life begins well, but the return of Napoleon brings separation, distrust, and danger to the Poldarks—and always for Demelza there is the shadow of the secret she does not even share with Ross.