On her first day at work Churchill's new secretary, Elizabeth Layton quickly angers him by failing to follow his instructions. Churchill causes Layton to cry and almost quit. After, his wife tells him that you have to be kinder to people as prime minister. King George VI
Although he was right about the danger from Adolf Hitler, Churchill has a poor reputation from the Gallipoli Campaign and supporting Edward VIII during the Abdication Crisis. Anthony Eden is among his few political friends; other Conservatives remember Churchill twice crossing the floor. Parliament dislikes the new Prime Minister's first speech promising "Blood, toil, tears and sweat" and Churchill refuses to negotiate for peace. He believes that the Germans are untrustworthy, but the French call him delusional for not admitting that the Allies are losing the Battle of France. Halifax and Chamberlain agree, keen to use Italian Ambassador Giuseppe Bastianini as intermediary to negotiate with Germany. During the May 1940 War Cabinet crisis they plan to resign from the government if Churchill refuses, causing a vote of no confidence that will allow Halifax to become Prime Minister.
The British Expeditionary Force is trapped at Dunkirk and Calais. Churchill forces a group of soldiers to a suicide attack to divert the attention of the Germans. Churchill then launches operation Dynamo. The Little Ships of Dunkirk rescue 300,000 British soldiers, but Belgium surrenders, France will soon surrender, a German invasion of Britain seems inevitable, but the US cannot help.
After having France defeated, the British now want to negotiate with Germany. Churchill then allows Halifax to speak to Bastianini. George VI unexpectedly visits Churchill; the King doesn't want to move to Canada or have Britain invaded. Still, not sure of what to do, Churchill suddenly decides to ask London Underground passengers about the war; the civilians reject negotiations and want to continue to fight the Germans. Churchill meets with other members of Parliament, who also support him.
With Layton's help, Churchill prepares to talk to Parliament, while Halifax refuses to go to war. At the end of the speech, he says that they shall fight on the beaches if the Germans invade. Everyone after that gives him support and waves their handkerchief.