Cowes Week, 1873; Jennie Jerome, a beautiful spirited young American, meets Lord Randolph Churchill aboard the flagship HMS Ariadne. There is an immediate and powerful attraction, and three days later Randolph proposes. Jennie accepts - but neither expect the total opposition they face to their engagement.

Jennie finds the Marlborough family overbearing and Blenheim Palace stuffy, but she knows as soon as her confinement is over she will resume her social life in London. A son, Winston, is born. Jennie's return to the London social scene is cut short by scandal...

Randolph's political career recovers after a stint in Ireland but having grown apart from her husband, Jennie embarks upon an extramarital affair with a dashing Austro-Hungarian nobleman, Count Karel Kinsky.

Randolph inexplicably resigns from his high post in the British government and begins acting more and more erratic. Soon, Jennie learns the horrible truth behind her husband's erratic behavior.