Zero and Stanley head towards God's thumb, periodically giving each other the thumbs up sign for reassurance as they walk. They carry Zero's shovel and four of the unbroken sploosh jars in the burlap sunflower seed sack. Zero often has severe attacks of stomach pain. Stanley spells words for Zero to keep him occupied. They climb up towards the thumb. At one point Zero uses the shovel to help Stanley up part of a cliff. This causes Zero, who is already weak and sick, to get big cuts in his hands.
Stanley and Zero continue towards the thumb but Zero throws up along the way.
Zero has passed out and Stanley leaves the shovel and jars on the ground so that he can carry Zero up the mountain. There is a bitter smell in the air and mud on the ground when Stanley reaches the top of the mountain. Stanley realizes that mud means there is water nearby and this renews his strength. He digs an onion out of the mud and he and Zero both eat half of it.
Stanley wakes to find himself in the middle of a giant meadow. Zero is still very sick but tells Stanley that it was he, Zero, who stole Clyde Livingston's shoes from the homeless shelter. He apologizes to Stanley and Stanley sings Zero the song that Madame Zeroni taught his great-great- grandfather.
Stanley digs up another onion and the narration shifts back to one hundred and ten years ago when Sam was selling onions. A woman thanks Sam for an onion remedy that saved her daughter's life. The narration shifts again to Stanley and Zero who spend two days eating onions and drinking dirty water from pools of mud. Stanley heads back down the mountain to find the shovel and jars he left behind. He is stunned at the distance that he covered while carrying Zero.
Zero gets better and tells Stanley that he was homeless before he came to Camp Green Lake. He often went to the homeless shelter that Clyde Livingston's shoes were in. Zero took the shoes because he thought it was better to take a pair of old shoes than to steal a pair of new shoes. He couldn't read the sign explaining whose shoes they were. Zero was wearing the shoes when people at the shelter discovered they were stolen. Everyone was so upset about the stolen shoes that Zero ran outside and places the shoes on top of a parked car. The next day Zero was arrested when he stole a new pair of shoes.
Zero and Stanley make a large hole for water with the shovel. Stanley realizes that he is happier than he has ever been before. He realizes he is happy he got arrested because now he has a friend and likes himself as well. Stanley thinks about secretly returning to camp and digging up the treasure that may be in the hole where he found the lipstick container.
Zero and Stanley pack water in the bottles and onions in the sack and plan to return to Camp in an attempt to dig up treasure and then escape. They wait until daylight before leaving. While they wait, Zero tells Stanley more about his life. Zero remembers his mother singing him the same song that Stanley sang, only with different words. One day Zero's mother left him in a park and told him to wait for her. He waited for a month, but she never returned. As they return to Camp Green Lake, Zero steers them in the right direction after Stanley takes a wrong turn. They reach camp and hide near the hole that Stanley found the lipstick tube in.
Stanley and Zero demonstrate their commitment to each other and their true friendship. They each make sacrifices for the other which show that they honestly want to help each other and are not just helping each other in order to attain some benefit for themselves. When they reach God's thumb it becomes clear that this is Sam's old onion patch, a place where, according to Sam, water runs uphill. At this point the real parallels between Elya Yelnats and Madame Zeroni's story and Stanley and Zero's story become clear. Elya Yelnats promised to carry Madame Zeroni up a mountain to a stream where the water ran uphill and then sing her the song about the wolf and the woodpecker. Although Elya never fulfilles this promise, his descendent, Stanley Yelnats, carries Madame Zeroni's descendent up a hill to a place where the water runs uphill and then sings him that same song. By doing this, Stanley demonstrates true dedication and perseverance, qualities that Elya obviously lacked when he broke his promise to Madame Zeroni.
The fact that Zero is the one who stole Clyde Livingston's shoes brings up the issue of fate. The set of coincidences that results in both Stanley and Zero being at Camp Green Lake is so extraordinary that it appears as if the hand of fate pushed a Yelnats and a Zeroni together again. While fate landed Zero and Stanley in Camp Green Lake, it is entirely their own actions of friendship that helped them to reach the onion field on top of the thumb-shaped mountain. A knowledge of history helps explain Zero's miraculous recovery atop the mountain. Sam once saved a girl who was suffering from stomach problems by giving her onion remedies and these same onions help Zero recover more than one hundred years later. This information reinforces the theme of cycles that repeat themselves throughout the ages. Another similarity between characters is the fact that Zero often went to the same homeless shelter that Clyde Livingston, the famous baseball player, once lived at. Being homeless is a clear disadvantage but the reader knows that Livingston went on to become a successful baseball player and it now appears that Zero might succeed as well. Zero has already improved his reading skills dramatically and it is obvious that he is naturally very intelligent. If he and Stanley escape Camp Green Lake then Zero has a good chance of becoming successful himself.