When dense smog cripples London for days and creates a serious health hazard, Churchill’s inaction leaves him vulnerable to his political enemies.

Elizabeth rejects protocol by appointing Philip to coordinate her coronation, but his ideas create conflict. The Duke of Windsor returns to London.

As the Soviets test the H-bomb, both Churchill and Eden have major health crises. Angry about her inadequate education, Elizabeth hires a tutor.

Elizabeth and Philip go on an exhausting world journey. Margaret takes over some of her sister’s official duties and tries to liven things up.

As tensions with Philip increase, Elizabeth spends time with her old friend Porchey. Churchill’s portrait is painted for his 80th birthday.

Margaret and Peter are reunited, but another obstacle stands in their way. Elizabeth is torn between her duty as Queen and her love for her sister.