After the dramatic events of Parts One and Two, Part Three tells us what happens next. Camp Green Lake is closed down and the Warden sells off the land, Stanley's father's invention is successful, and Zero hires a team of private investigators and finds his mother. The Yelnats family splits the treasure with Zero, and buys a new house with their half.
A year and a half later, we see Stanley at a party at his house: the family is celebrating a Super Bowl ad for Stanley's father's product. Clyde Livingston is at the party, and he stars in the ad. Zero and his mother are also there.
Part Three of this novel functions more or less like an epilogue, outlining the denouement of the story. The loose threads of the story are tied together in a perfect happy ending: Zero and his mother are reunited, the curse is broken, and the Yelnats family is finally prospering. Even Camp Green Lake is shut down, and no one will suffer there any longer.
It is interesting that Sachar's narration downplays this happy ending, preventing it from turning saccharine. He tells us that he will spare us the "tedious details" of the rest of the boys' lives, because it would be "boring" (230). Evidently, the denouement does matter, otherwise there would be no Chapter 50 and the story would end with the rainfall at the end of Chapter 49, but the author is right that the main action has passed - the fabulous and even supernatural events that took place from Lithuania to Camp Green Lake - and what remains is real life.