In the dying days of the Edwardian Empire, Christopher Tietjens enters into a destructive marriage with the beautiful but cruel socialite Sylvia. Ignoring her overt flirtation with other men, Christopher resolves to remain faithful to her, even when he encounters fearless young suffragette Valentine.

While Sylvia and Christopher are reunited publicly, their relationship remains turbulent in private. In the run up to war Christopher finds himself torn between his marriage vows and his feelings for Valentine.

In Rouen, an exhausted Christopher prepares soldiers for the draft. Back in London, Sylvia decides to visit her husband in France, oblivious to the consequences this will have for him.

Christopher is sent to the Front with McKechnie and Perowne. While Valentine waits for news of Christopher, Sylvia - now ensconced at Groby - makes one final, desperate play for him.