It is set against the backdrop of World War II, and looks at how Churchill's success as a great wartime leader ultimately undermined his political career and threatened his marriage to "Clemmie" - Clementine Hozier.

[4] The film proper begins shortly after the Second World War commences in September 1939, as Prime Minister Neville Chamberlain calls Churchill and Edward Wood, 1st Earl of Halifax, to a private meeting.

Chamberlain informs Halifax and Churchill that he knows he will be condemned by the British public for failing to recognize Hitler as a threat in time, and therefore intends to resign from office.

Though much-criticized for it at the time within his government, Churchill's decision hardens British resolve: with any idea of parley with the Nazis out of the question, the only route forward is to fight on until the end.

Churchill gathers influential members of the leftist Labour Party and convinces them to forge a coalition government, arguing that political and personal differences must be set aside to win the war.

Churchill soon after visits a Royal Air Force fighter squadron in the midst of the Battle of Britain, where he is well received by the young pilots until they are interrupted by a scramble call.

Churchill works relentlessly to persuade Roosevelt to bring the United States into the war, although this does not fully happen until the Japanese attack on Pearl Harbor on 7 December 1941.

Against his wife's strong objections, Churchill goes on the air and in a live radio speech condemns the Labour Party as being no different from communists and says that they would have to "resort to some form of Gestapo" to maintain control if they were voted into office.

Churchill broods over his fate, over the changing of the times and the gradual dissipation of the old way of life he holds dear, and admits that he feels lonely without a war to bring him purpose.

Out of office, feeling lost and betrayed by the very people he fought so hard to defend, Churchill is resentful and bitter while Clementine brings them both to attend a play in London one night.