The next morning Hazel and Augustus describe their meeting with Van Houten to Hazel’s mother. Afterward Hazel’s mom goes for a walk, while Augustus somewhat ominously suggests Hazel return to the hotel with him. On the way Hazel mulls over Maslow’s Hierarchy of Needs, which says that certain physiological needs must be met before a person can worry about other needs like love, self-esteem, and creating art. Back at the hotel, Hazel can tell something is wrong, and Augustus confesses that he is sick. Before the trip his hip was hurting, and in his last PET scan his body was lit up like a Christmas tree. Hazel hugs him and calls him “Gus.” Augustus says he will fight the cancer and be around a long time to annoy her. As Hazel cries he kisses her, noting that he had an apparent hamartia all along.
They lie in bed together and talk about treatments, and Augustus laments that he doesn't even get a battle. Hazel says the cancer is his battle and his war, but Augustus replies that the tumors are made of him the way his heart and brain are. It's a civil war with an inevitable outcome. He says before they left he viewed the Rijksmuseum online and that, for all the heroic martyrs, there was not a single painting celebrating someone dying of illness. Augustus concludes that there is no glory or meaning in dying of illness. Hazel thinks of how Augustus, whose body is dying but who still needs meaning, disproves Maslow’s Hierarchy.
On the flight home Hazel and Augustus look out at the clouds. Augustus used to dream of living on a cloud until a science teacher of his explained how harsh the environment is. He says the teacher specialized in murdering dreams. Before passing out from a mixture of champagne provided by the stewardess and pain medication, Augustus notes that it seemed like Van Houten was personally mad at them. The flight lands and soon Hazel is back home watching television with her father. He reveals that he found out about Gus's recurrence of cancer from Gus's mother before the trip. He also read An Imperial Affliction, which he found a little confusing and slightly defeatist. When Hazel says the book was honest, he contends that defeatism and honesty are different things. He isn't sure what he believes, but he remembers a math class that led him to believe the universe is biased toward consciousness and wants to be noticed.
The following day Hazel and Isaac meet at Augustus’s house. The three catch up while Augustus receives a cocktail of chemo drugs through a PICC line. Eventually the conversation turns to Isaac’s ex-girlfriend Monica. She hasn't contacted Isaac at all since he had his eye removed. Augustus is furious, and shortly after they're driving to Monica's house, where they spot her car in the driveway. Augustus, who has a carton of eggs, gets out of the car with Isaac, and the two egg Monica's car. Hazel snaps a picture of Augustus just as the door beyond him is opening to reveal Monica's mother. It's the last picture she ever takes of him.
Hazel and her parents eat dinner with Augustus and his parents at Augustus’s house. Throughout the meal Hazel and Augustus reminisce about their magical experience at Oranjee, where they say the food tasted as if god had prepared it.
One week later Augustus is admitted to the ER with chest pains. Hazel, dressed once again like Anna, goes to visit him. His mother only wants family in the room for now, however, so Hazel stays in the waiting room in order to be close. While she waits, Hazel looks at pictures on her phone and thinks how it seems like forever ago that she met Augustus. The significance of Van Houten’s words about some infinities being bigger than other infinities dawns upon her. Two weeks later Hazel takes Augustus back to the Funky Bones park in a wheelchair. They drink a bottle of champagne given to Augustus by one of his doctors. They watch the children play. Augustus says during their last picnic he imagined himself as one of the playing kids. Now he imagines himself as the bones.