What is the major conflict, setting, and theme in The Hitchhiker's Guide to the Galaxy?
As previous answers have stated, there is a lot going on in this book—lots of plots and subplots, settings, and themes.
When we first start out, coming from the relatable perspective of Arthur Dent, it seems that the major conflict of the story may be that his house is going to be destroyed. But, very shortly after, we learn that the entire planet Earth is going to be destroyed, and that takes precedence. Following Earth's destruction, and Arthur and Ford's escape from it, there is a lot of conflict between different groups from all over the galaxy—the Vogons, Zaphod Beeblebrox, etc.
What this is all building up to is the plan that Zaphod's left brain left for him, and the search for the Ultimate Question of Life.
Settings include Arthur's home, Earth, the Vogon ship, The Heart of Gold (another ship), and the planet Magrathea.
The most major theme in the book, and the one that makes it such an unforgettable classic, is that life is absurd. Another big theme is the clash of cultures, which is greatly aided by having sections of the actual Hitchhiker's Guide to the Galaxy dispersed throughout the book, giving the reader information about life in different parts of the galaxy, and showing us how little humans know, isolated on their planet.
The Hitchhiker’s Guide to the Galaxy is a comical adventure novel with overt and subtle conflict, multiple settings, and overarching themes involving meaning and perseverance. The setting of this book is the entire universe. The characters spend much of their time on Zaphod’s ship, Heart of Gold, and explore a planet called Magrathea, but all the action of the story takes place as an adventure through space. Douglas Adams writes conflict into the story by making Arthur Dent a man with little confidence. For example, Arthur can barely summon the courage to talk to Trillian at the party where he first meets her and Zaphod. Arthur constantly navigates scenarios complicated by his lack of confidence. This conflict ties in nicely with the theme of meaning, specifically man’s insignificance in the larger universe. Arthur’s internal conflict is exacerbated by the reality that humans are irrelevant in the scope of the universe. Adams combines his first theme with a second theme of perseverance. While the five main characters in this book get into a continual stream of trouble, from planet destruction to death-defying escapes, they forge ahead through each problem.
The settings for The Hitchhikers Guide to the Galaxy are diverse. Two major ones are Arthur Dent's house in England and the space ship, the Heart of Gold, that picks Arthur and Ford Prefect up at the beginning of their adventure. The major conflict in the novel is the many manifestations of a bureaucracy at conflict with humanity. It begins with the bulldozers at Dent's garden gate and continues through all the intergalactic misadventures, including Zaphod Beeblebrox's abduction of the Heart of Gold. A major theme is the struggle for rational development of reason in situations that seems absurd and without meaning.
Most of the book is spent on the Heart of Gold, the ship that Zaphod Beeblebrox steals, but other places are visited. A major conflict of the story (and series) is that Zaphod does not understand why he does this, and all attempts to find out lead him to discover that he's not supposed to know. Another conflict is Arthur Dent's confusion, first at his planet's sudden destruction and then at being in a universe that's much bigger and more complex than he ever wanted to know. He is forced to just go along with everything without even a decent cup of tea. The major theme is that humans are all like Arthur Dent, having no hope of ever figuring out the universe but doing well when trying to survive.