The unnamed Narrator lives in Woking, outside of London, in the early twentieth century. He tells the story of an invasion of Earth by Martians. The events start at the end of the nineteenth century, while Earth is being observed by Martians. Resources on Mars are running out, and the Martians, with superior technology, plan to conquer Earth. Astronomers witness the venting of gases on Mars, not knowing that it is the Martians launching their attack. 

A falling star lands near the Narrator’s home and he goes to investigate. Several other scientists have already started inspecting the strange object. It is a long metal cylinder with an endcap the size of a table. When the endcap begins to unscrew itself, the scientists conclude that it must have travelers inside. Crowds of people gather, and eventually strange Martians exit from the cylinder. The Narrator later discovers that these strange beings are actually vehicles that the Martians pilot (only part of the large “creature” that everyone sees is actually the Martian).

While the scientists are trying to communicate with the Martians, a strange device rises from the pit. The Martians use a Heat-Ray to instantly incinerate anything in its path. They sweep the ray around the pit, burning the scientists and almost all the gathered people. The Narrator narrowly escapes. He runs home and tells his wife.

Life continues for those around the area of the crash site who are unaware of the danger that the Martians pose. A military regiment has been activated, and artillerymen are deployed to investigate. A second cylinder streaks across the sky and lands nearby. When fighting breaks out between the soldiers and the Martians, the Narrator decides to flee to Leatherhead (another town on the outskirts of London) with his wife. He borrows a horse and cart from a neighbor and rides for the remainder of the day. After leaving his wife with family, he travels back toward Woking to return the cart and horse.

On his approach to Woking, the Narrator sees a third cylinder streak across the sky. Two large vehicles crash through the trees nearby, and he swerves and topples the cart, killing the horse. He hides until the vehicles have passed and runs to his home. The Narrator notices an artilleryman hiding outside of his home and invites the man inside. The artilleryman tells the Narrator about how the Heat-Ray instantly destroyed his artillery emplacement. The artilleryman and the Narrator leave the next day. In a battle at the Thames river, one of the Martian vehicles is destroyed. The Martians retreat with the wrecked vehicle and the Narrator barely escapes, eventually hiding in building with a curate who behaves in a deranged manner.

The Narrator describes his brother’s escape from London. The Narrator’s brother is part of a mass exodus that is extremely dangerous, not just for the Martian vehicles, but also for the six million citizens trying to flee the city. The Narrator’s brother saves two women from robbers and the three of them eventually escape on a steamboat leaving the Essex coast.

The Narrator and the curate travel through the outskirts of London, hiding from the Martians. As they hide in a building that has a well-stocked pantry, another cylinder from Mars lands outside and destroys half of the building. The Narrator and the curate are trapped inside, but they can watch the Martians through a small crack in the rubble. The Narrator watches the Martians closely. The curate, who was already showing signs of insanity, becomes even more disturbed each day. He also refuses to ration the food. After several days, he starts yelling, and the Narrator knocks him unconscious. The noise attracts one of the Martians, who drags the curate's body away. The Narrator hides in the coal-cellar and is almost discovered.

After days of silence, the Narrator leaves the ruined building and finds that the Martians are all gone. He wanders the burnt landscape looking for food. He comes across the artilleryman that hid at his house. The artilleryman describes a future where humans must live underground and prepare to overthrow the Martians someday. The Narrator finds the artilleryman's plans unsettling but agrees to help him because he wants to have a purpose again. However, the Narrator changes his mind the next day and wants to find his wife. As the Narrator passes through London, he sees no sign of the Martians. He discovers that the Martians have all died from bacteria, as they had none on their home world. 

People flood back into the city, and the Narrator is nursed back to health by a helpful family. He hears that Leatherhead was destroyed. He leaves the family, returns to his home in Woking, and finds his wife. The Narrator ends his story by saying that the Martian attack was actually beneficial, as it let humans know that there are threats on other planets. He is still haunted by all the death and destruction that he has witnessed.