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.

Vicious rumours about Christopher abound, leading to tragedy at Groby. Sylvia finds a new admirer who proves a distraction as the war continues, and Valentine moves to London. Meanwhile, Edith and MacMaster plan a new life together.

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.