Stanley and Zero put four unbroken jars in the sack, just in case. Zero carries the shovel and is unworried when Stanley warns him that he's unlucky. Zero insists they can only go up from where they are. Not long after they set off, Zero has another episode. Stanley feels as though God's Thumb isn't getting any closer and realizes that even if they do make it, they'll have to climb it. Zero begins using the shovel as a cane as the boys wonder who Mary Lou was.
Now that Stanley and Zero are removed from the camp itself, the shovel becomes a lifeline instead of acting as the boys' sentence. This again shows that the camp has the power to corrupt even the most normal and mundane of garden tools and turn them into something horrific and toxic.
Zero has another episode and Stanley wonders if he'll have to dig Zero's grave. He's surprised when Zero gets up again. Zero asks Stanley to spell words for him to sound out, and the spelling seems to distract Zero from his pain. They stop when they're so parched it hurts to talk. Stanley wonders if the bad bacteria only contaminated the jars that were easy to open. He thinks he's not afraid of dying or the pain, but he is afraid of his parents not knowing what happened. He wonders if the Warden will send out a search party and reasons that he at least has a family who will care, unlike Zero.
It's worth noting here that as Stanley thinks about his own family and Zero's lack thereof, he very clearly believes what the Warden says about Zero—even though she's proven herself to be untrustworthy, nasty, and dismissive of non-blood relationships that may be just as fulfilling. This offers hope that there is actually someone besides Stanley who can care about Zero; whoever that person is just isn't on the Warden's radar.
Zero wonders what's at the top of God's Thumb, and Stanley suggests there's probably an Italian restaurant there. The boys joke about what they'd order. A few hours later, they reach the west edge of the lake. Unlike on the other side, this edge is a steep cliff. They decide to try to climb up using a series of ledges and Zero miraculously manages to keep up. When they reach a large flat ledge, Stanley realizes that the next one is several feet above his head with no footholds.
Though the ledges and footholds are very difficult for Stanley and Zero to scale, it's also important to recognize that there are, at the very least, ledges and footholds—in short, nature is helping them out here by offering them a way up the lake bed.
Zero suggests that Stanley boost him up, and then he can pull Stanley up with the shovel. Boosting Zero up works, and Stanley uses the shovel handle to help him walk up the wall. Zero somehow helps pull him onto the ledge. Stanley notices blood and realizes that Zero cut his hands holding onto the blade of the shovel while Stanley climbed. Zero drinks the blood. They rest and then climb the rest of the way up. The sun looks like it's resting on the top of God's Thumb.
As the sun moves and gets closer and closer to God's Thumb, it acts as a beacon that Stanley and Zero can follow. Again, this is another way that the natural world appears to be helping the boys reach God's Thumb. The boys' teamwork reinforces the power of their friendship to achieve common goals.