A frail and elderly Margaret Thatcher is at breakfast with her husband Denis. The small change of married life comprises their sporadic conversation. We glimpse the house staff and perhaps assume Thatcher is still at the height of her powers if no longer actually in office but their attitude doesn't seem to correspond; they are not disrespectful, but neither are they deferential and we seem to be in some kind of superior retirement home. Thatcher peeps through the door but cannot make sense of what is happening outside and nor can we. From the window we see with her the comings and goings of security staff, presumably Thatcher's personal protection team. It is only in a reverse shot when a woman finally comes to the Thatchers' door and inquires if everything is alright that we see no-one is at the table where Denis was sitting only a split-second earlier.
Thatcher shops for milk at a convenience store. She seems bewildered by the price, talking about it to no-one in particular, and neither staff nor fellow customers seem to recognise her; to them she seems to be just another irritating old woman. One is impatient to the point of rudeness at being held up by her fumbling for the change to pay for the pint that is her only purchase. The scene has an air of unreality as if a dream sequence.
Back at the house, overheard snatches of conversation make it clear that the staff are dismayed that Thatcher had escaped their oversight to make this impromptu excursion into the real world outside unescorted and thereby confirm that it wasn't a flight of fancy on her part. Still a symbolic if clearly diminished figure, looking after her seems to be no more than a necessary nuisance to those around her.
Thatcher as a girl in Grantham experiences a second world war air-raid. She takes a not-inconsiderable risk as exploding bombs shake the house to leave the relative safety of the cupboard under the stairs but only to prevent some produce from spoilage by putting it away rather than to protect it from the raid as such. Later we see her as the focus of unkind remarks by her classmates from their point of view on the other side of the road. She seems isolated from them socially.
In a large hall, now a young woman Thatcher is flirted with by Denis as a young man. They discuss marriage and his support for her apparent political ambition is made clear by him. He soon proposes. We later see them at the theatre together, talking and joking. At a meeting, she is patronised and condescended to by the local Tory party grandees who clearly don't take her application to be the candidate for parliament very seriously but she is unabashed. As a grocer's daughter, she points out, she knows the cost of living and how to budget and will thus appeal to the housewives in the electorate. Compared unfavourably with another, military gentleman candidate she avers that she also faced danger during the war.
In parliament as a young Tory minister she rounds on the opposition politicians who have failed to offer her the respect she feels she deserves by lecturing them on their failure to attend to the content of her words rather than the manner in which they were delivered but her raised voice is gratingly strident and high-pitched.
We witness a cabinet meeting with prime minister Edward Heath. Thatcher is quietly competent in her contributions but clearly a junior member of the government, seated as she is at the very far end of the cabinet table and having to lean forward to be seen by Heath who seems at first hardly to recall who she is.
In a private meeting, two unnamed advisers counsel Thatcher to consider standing for the leadership of the Tory party; she is incredulous. She is next seen in a voice-coaching session. Advised to deepen her delivery and inject authority, she calls 'Denis!' loudly, in a notably lower timbre, and he visibly jumps in his chair although on the far side of the large room. The advisers smile in satisfaction.
It is winter 1979. We see news headlines and archive footage about strike action. Leicester Square in central London is piled high with rubbish bags and Thatcher witnesses people stopping in cars to throw theirs on the pile on the pavement in front of her as she walks by while those around express concern at the smell.
Her daughter Carol visits the elderly Thatcher and they discuss starting to sort through Denis's clothes and shoes so they can be sent to a charity shop. The task seems overwhelming to Thatcher both physically in terms of volume of material but also emotionally. She tries to speak to son Mark but cannot reach him by telephone.
Thatcher speaks with one of the advisors in the Palace of Westminster underground car park as he is already in his car leaving. He drives away towards the exit ramp and Thatcher turns to walk to her own car but almost immediately there is an explosion and we cut to the car in flames outside; newspaper headlines tell us it was Airey Neave, victim of a car bomb.
Pinafored and standing at the kitchen stove Thatcher yet incongruously speaks of state matters and the need to attend to them. Denis complains of her absences from family life and testily shouting that she shouldn't worry about them (her family) storms off.
After much industrial unrest the miners are now on strike. A beleaguered Thatcher is driven away in her limousine through protesters holding placards bearing anti-Tory slogans as some hammer on the car's roof and windows, shouting angrily at her, faces contorted with rage and hatred.
The elderly Thatcher watches a DVD of Carol and son Mark as children playing on the beach.
After Argentina invades the Falkland Isles Thatcher has summoned the military top brass, determined to find whether it is possible to recover the islands. The consensus being that it is, if only barely, but is perhaps also inadvisable, Thatcher makes it clear that it must be done. Political speeches to parliament and scenes of preparation and the sailing of the task force follow. In a council of war she is given news of the Argentine ship the General Belgrano manoeuvring in the vicinity of the Task Force. Advised that it is a threat, she gives the order to sink it.
The elderly Thatcher speaks to a doctor. She comments acidly on his modern phraseology, comparing it unfavourably with the plainer and more meaningful language of her prime. He asks her about symptoms of dementia, including hallucination. Having by now witnessed numerous scenes where she has plainly imagined the dead Denis, we note her vague discomfiture as she says no, but her mental faculties seem acute enough; Thatcher is apparently now aware that she is imagining him. We begin to doubt that she has either Alzheimer's or any other form of dementia.
Cabinet members openly worry about their political careers because the government is so unpopular. Thatcher upbraids them for their lack of principle. Apparently on her way to a public appearance, Thatcher requires the aid of a seamstress to mend her clothing. She thanks Crawfie by name. We see her moments later as part of a cabinet group portrait, the cabinet members now smiling around her.
The elderly Thatcher is hosting a dinner that includes former political colleagues. At the head of the table, she seems prime ministerial and asked to comment on Islamic extremism is forthright in her advocacy of resistance to it but seems for a moment to forget she is no longer premier as she speaks of what we must now do. There is a slightly embarrassed silence. Carol tells her plainly that she is no longer prime minister.
We are at the Tory party conference in Brighton. It is very late, the early hours of the morning, and Thatcher continues to work in her hotel suite on important papers as Denis retires next door to bed. There is a sudden explosion apparently centred on the bedroom and the rooms of the suite disintegrate. Thatcher is distraught with concern, shouting for Denis who it seems must have died but he soon re-appears, unhurt and spirit unshaken, ruined shoes in hand (he had apparently been putting them outside the door to be cleaned and thus avoided the blast).
The elderly Thatcher now always talks to Denis in the full knowledge that she is imagining him and he answers in kind, challenging her to make him disappear. She switches on all manner of domestic appliances, radio, television and hi fi to drown him out. When we return to where he was sat he has gone.
Stalking the corridors of power Thatcher now seems isolated, glanced at menacingly by former trusted political friends and murmuring darkly about plots against her. The end of her political reign seems at hand.
Suffering insomnia, Thatcher begins the herculean task of sorting through Denis's belongings. By morning it is done, to Carol's amazement when she arrives later.
In the final scene of the film, Denis pads down the hallway barefoot, the last pair of shoes now in his hand, stopping at the far end to put them on and although Thatcher now begs him to stay, walks away telling her she will be all right.