Thoreau moves to Walden Pond and decides to embark on a personal experiment. His objective? To see what will happen if he lives alone, with just the bare essentials, for two years. Pretty exciting start, actually. Definitely makes Shmoop want to keep reading.
Our author finds that he can't totally escape from civilization on Walden Pond, since he's so close to the town of Concord, MA. Still, this turns out to be a good thing. By embarking on his spiritual quest so close to home, he can show how enlightenment is possible for anyone. As we can see, conflict doesn't always have to be a totally bad thing. A lot of good can come of it.
On one visit to the village, Thoreau gets arrested for tax evasion. He spends just a few sentences on his arrest, which ends with him spending a night in jail. It's not a huge setback for his Walden Pond project (so it's more of a nuisance than a complication, actually), but he does go into a lot more depth about the incident in another essay, "Civil Disobedience."
In the winter, Thoreau is almost completely isolated, hemmed in by snow. So he is compelled to simplify to a degree he hasn't simplified yet. He's stuck in his cabin for a week at a time without company. Characteristically, Thoreau finds joy and beauty in all that snow. This isn't the kind of Die Hard moment we think of when we hear climax, but in a book about isolation, it certainly serves as the climactic moment.
The thawing of Walden Pond at the end of winter is one of the most dramatic scenes in the book. It marks a kind of spiritual turning point for Thoreau, a way of letting go of winter and past regrets and looking ahead to the spring and the future. Again, it's no horror story suspense, but it allows us to wonder what will happen when spring arrives.
When spring arrives, Thoreau leaves Walden Pond, but he admits he's not really sure why. Having lived this particular life to the fullest, he suggests that he's going out into the world to discover other ways of living.
At the end of his book, Thoreau draws some conclusions about life, the universe, and pretty much everything else. Walden actually ends with a whole chapter where Thoreau reflects on his past experience, and what he hopes his readers can learn from his experience. Generally, he announces that his private experiment is a success, a confirmation of the beliefs he laid out in early chapters such as "Economy."