The narrator is a middle-class educated man who writes philosophical papers and is interested in science. He values education, often commenting on the level of education of the people he encounters, as well as any lack of ability of logical reasoning he observes. The narrator recounts his experiences during the invasion of England by Martians, as well as those of his younger brother in London. He compares the Martian treatment of humans to humans' treatment of animals, and he believes the Martians to be more highly evolved. The narrator is motivated to survive to be reunited with his wife, from whom he is separated for the majority of the tale. Just as he is about to lose hope, he approaches a Martian, expecting it to kill him, but the Martian dies. He discovers all the Martians have been killed, and he returns home after a period of mental breakdown to find his wife has survived.
The Martians fled their dying home world to inhabit a new place. They are portrayed as cold, ruthless, and highly intelligent. Their bodies are octopus-like, mostly a large head with tentacles. They move with difficulty outside of their machines. Their technological capabilities far exceed those of humans, whom they view much as humans might view insects. The humans they do not eradicate with weapons serve as sources of blood, which they inject directly into their own bodies from living victims. The Martians have no resistance to the bacteria of Earth, which eventually leads to their demise.
The younger brother of the narrator lives in London, where he studies medicine. He becomes increasingly alarmed about reports of Martians in his brother's hometown but is unable to reach him. The narrator's brother is forced to flee when the Martians reach London. He comes to the aid of Miss and Mrs. Elphinstone, and the group manages to escape the Martians by sea after witnessing the dramatic destruction of two tripods by an ironclad ship.
A driver in the artillery, the artilleryman missed being hit by the Heat-Ray when his horse fell because of a rabbit hole. After the narrator calls him into his house to hide, the two escape Woking. They are separated at Weybridge, where they encounter some tripods, one of which is destroyed by a shell. He manages to evade the Martians and creates a stockpile of food while making plans for the survival of humanity, which involve living in the drains under London. He doesn't actually do much work to make his plans a reality.
The curate is the preacher of a church in Weybridge that is destroyed by the Martians. He is at a loss to explain how such a disaster could befall him, but he comes to believe the invasion to be God's judgment. He gradually loses his mind when he is trapped in the collapse of a house with the narrator for many days, in close proximity to a group of Martians. He begins to rave loudly, and the narrator knocks him out. Martian tentacles drag his body from the house, and he is killed.
Ogilvy is an acquaintance of the narrator who invites him to an observatory to use a telescope to examine Mars. They both see an explosion that turns out to be a cylinder launching toward Earth. Ogilvy observes the fall of the first cylinder and is the first at the landing site. He leads a group of men to excavate the cylinder before it opens, revealing the nature of the Martians. He then leads a group of men to approach the Martians with a white flag of peace only to be incinerated by the Heat-Ray.