The Moon Is a Harsh Mistress is the story of the successful revolution of the Lunar colonies against the Lunar Authority on Earth. It is presented as the memoirs of one of the architects of the revolution, Manuel Garcia O’Kelly Davis, known throughout the novel as Mannie.
A computer repairman with virtually no interest in politics, Mannie appears to be the least likely of Luna City’s citizens to become involved in a revolution against the oppressive Authority. He hates it as much as any other Lunar Citizen, or “Loonie,” but sees its interference as inevitable. One day, however, he stumbles into a secret meeting of a revolutionary group, following a tip given to him by the main computer at Lunar Authority Complex. This computer, which Mannie has named Mycroft (or Mike) after Sherlock Holmes’s elder and smarter brother, recently became self-aware, developing a humanlike personality. Mannie keeps that unprecedented development to himself.
When the secret meeting is interrupted by the Lunar Authority’s armed guards, Mannie helps one of the agitators escape. She is Wyoming “Wyoh” Knott, a tall, blonde woman from Hong Kong Luna whose beauty charms him. Ducking into a hotel room to escape detection, Wyoh and Mannie continue the political discussion, his cynicism clashing with her idealism. Nevertheless, they have enough of a common cause for him to trust her with his secret that the main computer has “come alive.” Professor Bernardo de la Paz, Mannie’s former mentor, joins them in the secret, and with his knowledge of revolution theory, combined with Mike’s knowledge of quite literally everything else, they plan the Lunar revolution.
Taking over the Authority offices on the moon is relatively easy, though the date of the coup has been rushed, precipitated by the rape and murder of a Lunar woman by Authority Peace Dragoons. The guards are killed, and the Lunar Authority’s representative, Warden Mortimer Hobart, suffers an irreversible coma. For the first time in history, Loonies control Luna.
Authority on Earth is still to be reckoned with, however. Mannie and the professor come down to Earth to negotiate peace, but the negotiations fail. Having no weapons, the Loonies catapult moon rocks toward selected targets on Earth. The rocks hit with the force of bombs, and Earth governments capitulate. The Loonies thus win the Lunar revolution.