The plot is nice and simple: a German scientist named Otto Lidenbrock discovers a sixteenth-century runic manuscript by a famous alchemist that brags about a journey into the Earth. Our narrator is Lidenbrock’s young nephew Axel, who is in love with Lidenbrock’s goddaughter Grauben and doesn’t want to do much else other than marry her. Bullied by the monomaniacal professor, Axel manages to decode the scroll, and then Lidenbrock drags him off to Iceland to descend into the Earth’s interior through a crater. They also pick up a stoical Icelandic hunter named Hans as their muscle.
Within the Earth, they go through a series of misadventures: bouts with thirst, epic climbing, giant mushroom forests, massive underground bodies of water, mastodon herds and giant men. There’s also a fair amount of geology lecturing as they view the Earth’s strata during their descent. The science is obviously out of date – I’d give a pass to Lidenbrock’s theory that the center of the Earth is cool because the whole conceit rather depends on it, but other ideas, like a warmer outer space, jump out as pretty flawed even in the context of the time (there’s even a bit of racist phrenology). Still, overall it’s a fun way to learn about concepts and spotlight a relatively new science.
The characters are probably the best part of the novel. Not that they’re nuanced explorations of human psychology in any way; actually they’re quite the opposite, but they’re damned entertaining. Lidenbrock is an excellent early example of the eccentric scientist (in nineteenth-century literature, he fits the mold a lot better than Shelley's Frankenstein); I know that Doc Brown from Back to the Future has a lot of Lidenbrock in him. He’s excitable, obsessed, impatient, focused on his theories over anything else, but capable of some compassion and love for his wards Axel and Grauben. Hans is basically Brock from the Venture Brothers, and Axel’s reluctance to go on the adventure and efforts to get out of it make him relatable and funny.
The plot does lack structure though, especially in the second half. The characters get underground, encounter some weird stuff, then Verne seems to lose interest and quickly wrap things up. Maybe this is a product of serialization? The novel doesn’t quite fulfill its potential in this rushed ending. However, it does nicely embody the values of science fiction: take the wisdom of the day and put a twist on it to tell an entertaining or enlightening story. The focus is on “entertaining” with Verne, but there’s nothing wrong with that.