Alan Moore's novel V for Vendetta is a futuristic portrayal of life in Britain after a nuclear war. It is told in three parts and is a rather complicated and complex story of intrigue and terror.
A teenage girl named Evey Hammond who, in her desperation, finds herself in trouble with the law, is rescued by a masked man named V. He is clearly a kind of terrorist who is methodically killing his targets. He wears the mask and a costume/uniform to disguise his true identity.
A detective named Eric Finch begins investigating V and his activities and discovers V's targets are all connected to a place called Larkhill, a kind of resettlement camp; he also discovers that V was once an involuntary inmate at the camp, where he learned how to make the lethal gases he is now using in his attacks. In the midst of his terrorist activities, Evey begins to fall in love with V, and he leaves her alone in London to fend for herself.
V's earlier killings are just a cover for his real goal: anarchy. He wants to eliminate the corrupt post-apocalyptic government and create the "Land of Do-As-You-Please," so he begins striking government targets in his quest for anarchy. His tactics begin to work and the people begin to riot and loot.
Finch disappears for a time, secretly revisiting the camp at Larkhill where--through the use of psychotropic drugs--he is able to deduce where V is hiding. He finds V and shoots him, though V claims the shooting is in vain because V is an idea, and ideas cannot be killed by mere bullets. He dies later in Evey's arms.
Evey dons V's mask and outfit and appears as him in front of crowd; she announces a plan to bomb the Prime Minister's residence. The bombing happens as planned the next day. Evey has assumed the persona of V, and she intends to train Finch's partner, Dominic, as her successor.