June 1770: The Spanish eject the British garrison from Fort Egmont on the Falkland islands.

In London, the government orders a fleet be prepared and authorises the use of press gangs to gather suitable recruits.

In a tavern, a young gentleman named Blanding reads a verse he has composed advocating military action against Spain. He banters with Dr Samuel Johnson, who sits glumly by the fire. Johnson's publisher asks him when his next essay may be forthcoming and Johnson tells him that he now has his subject: madness.

On leaving the tavern, Johnson sees a press gang carrying a man away. He gives money to a war-crippled beggar, who himself advocates further war.

At home, Johnson sets about his essay and is trouble by a dream of a serving boy being taken by the press gang. His housekeeper wakes him in the morning to report that he has been summoned by Lord North, the prime minister.

The prime minister tells Johnson that the Spanish have agreed terms to avoid a British military response. They will evacuate the Falkland islands and allow the return of the British garrison. The prime minister tells Johnson that his publisher had written to request a seat for Johnson in parliament. Johnson says he would like this but that he would not be able to follow a party line. He says all politicians are liars.

The prime minister tells Johnson that the country cannot afford a war. They both recognise that war would also lead to the Tories, in opposition, coming to power, and that they would be unlikely to continue Johnson's government pension. The prime minister asks Johnson to write a pamphlet to convince the public of the case against war.

Parliament is unhappy with the peace agreement, particularly in view of the great expenses incurred in preparing for war. One MP points out that the convention makes no reference to British sovereignty over the Falkland islands, only occupation of Fort Egmont. The press is even more scathing.

Johnson begins to read of the convoluted history of the possession of the Falkland islands. His housekeeper is concerned by the household's unpaid bills but Johnson is uninterested. He goes to watch parliamentary debate. There, one MP suggests that Britain had been the aggressor, to great disapproval. He claims Spain had right to the Falklands by virtue of prior occupation and advocates surrendering the islands.

Johnson meets with the prime minister again and notes that the sides in the debate now seem balanced. They observe Lord Chattham, the pro-war opposition leader, conferring with a writer who, under the pseudonym Junius, writes scathingly of the situation in the press. Johnson is outraged by the man's work. The prime minister implores Johnson to use his similar talent to answer such arguments but Johnson remains uninterested.

That night, Johnson dreams again of the servant being abducted by the press gang.

Junius writes persuasively against the peace convention and is read widely. Johnson's publisher implores him to respond to it, but Johnson remains aloof.

In a tavern, Johnson hears how Blanding was carried off by the press gang. When he gets home, the prime minister is waiting for him. He is stern: he must write a response to Junius or lose his government pension. Johnson reports he had already decided to do it, for his own reason, to dispel a nightmare of his servant dragged away to sea and perishing, legs smashed, on the deck of a burning ship. He writes the pamphlet with vigour.

The pamphlet sways opinion and parliament votes in favour of the peace agreement.

Afterwards, the prime minister orders sales of the pamphlet to stop. When Johnson asks why, he says he objected to the besmirching of a dead man's name in the pamphlet. Johnson reports that he has a new relish for politics and asks for a seat in parliament, but the prime minister declines. He discloses that under a secret deal with the Spanish, he will withdraw British forces from the Falklands in a few years. He hopes no one need ever go to war, or write about, the Falklands islands. As Johnson departs, the prime minister notes the disturbing power of his writing.