An unnamed writer, living near Woking in Surrey, recalls the days when no one suspected that intelligences far greater than human ones were watching the Earth and preparing to take it. Astronomers see flashes of gas leaving Mars, and soon a falling star buries itself on Horsell Common. It is a metal cylinder, and as a curious crowd gathers, its lid unscrews and the first Martians, heavy and labouring under Earth's gravity, struggle into view.
The early wonder turns to horror when a deputation carrying a white flag is incinerated by an invisible heat-ray. From the pit the Martians assemble towering three-legged fighting-machines that stride over trees and houses, scattering flame and a suffocating black smoke. Artillery destroys one machine but cannot hold the line, and the narrator, having sent his wife to safety, is swept into a flight across a countryside that is rapidly becoming a battlefield.
The collapse spreads outward. In chapters narrated through the narrator's brother in London, the capital empties in a vast, trampling exodus as millions try to escape at once, and the warship Thunder Child rams two machines before it is destroyed. Order, communication, and government simply stop. Two human responses dominate the ruin: a curate who breaks down into hysterical despair and is finally killed when his noise threatens to betray their hiding place, and an artilleryman who insists the war is already lost.
Trapped for days in a wrecked house beside a fresh Martian pit, the narrator watches the invaders feed on human blood and learns to see his own species as livestock. Later he meets the artilleryman again, who lays out a grand vision of survivors living underground, learning the enemy's machines, and breeding a new disciplined race. The narrator is briefly inspired, then sees that the man does little but talk, drink, and dig a tunnel that goes nowhere, and he walks on alone into a silent, weed-choked London.
Driven near suicide by the desolation, the narrator climbs toward a Martian redoubt on Primrose Hill and finds the invaders dead in their machines, killed by the putrefactive and disease bacteria of an Earth they could not resist. Mankind survives almost by chance. In an epilogue the narrator, reunited with his wife, weighs the lasting unease the invasion leaves behind, the gifts it brought to science, and the sober new knowledge that the planet was never a safe and fenced-in home for humanity.