Genre
Post-Apocalyptic Science Fiction
Setting and Context
England, 1950s, during the Cold War
Narrator and Point of View
Third-person singular, with emphasis on Bill, the protagonist.
Tone and Mood
The tone of the book starts out in a jaunty and irreverent tone, but rapidly turns dark.
Protagonist and Antagonist
Bill is the primary protagonist of the book. The primary antagonists are the murderous Triffids, however the cynical Beadley is the main human protagonist.
Major Conflict
After a bizarre meteor shower renders most of Earth's population blind, some mobile and venomous plants prey on the survivors.
Climax
Most of Bill's problems come not from the relatively unintelligent Triffids but from his fellow human survivors. The climax of the book is when representatives of the new government takes Susan hostage in an attempt to force Bill and his colony to join them.
Foreshadowing
When Wilfred Coker kidnaps some of the survivors who can still see, the violence and deception he uses to advance his agenda foreshadows the strategy of the new government, which relies on force and intimidation.
Understatement
The phrase "something is seriously wrong somewhere", which appears in the first sentence of the book, understates the problem. Something-- specifically the mass blinding of most of humanity-- is catastrophically and apocalyptically wrong. The world as the main character knows it has completely changed, and not for the better. Like the zombies in the more recent TV series "The Walking Dead", the triffids are an ongoing force that preys upon the human survivors, who turn out to be more interested in harming and competing with one another than they are in retaking their world.
Allusions
The book was heavily influenced by "The War of the Worlds", and the threat of an invasion by an inherently foreign force from outer space came from H. G. Wells.
Imagery
Blindness imagery is everywhere, and it's used allegorically to suggest a sort of emotional and spiritual blindness particularly in the ideology of the most successful sighted survivors.
Paradox
Among the people Bill encounters is a genuinely blind man, who uses a white cane and who is unaware that large numbers of people have been affected by the meteor shower and cannot see.
Parallelism
As the triffids pick off blind or other helpless individuals and grow in numbers and apparent intelligence, groups of ruthless human beings band together and begin to take over.
Metonymy and Synecdoche
The chaotic hospital, with its blinded staff, is representative of the whole of London, which in turn represents all of England including the countryside. Groups of blind people are represented as a cohesive unit, particularly in Coker's group where sighted individuals are forced to serve groups of scavenging blind people.
Personification
Different individuals personify their ideology. Miss Durrant, for example, personifies the self-sacrificing (and somewhat religious) notion that as many people as possible must be saved, regardless of the risk to the group. For this reason, her group is overwhelmed by helpless and needy people until there are not enough resources or labor (from sighted people) to go around.