Hazel Grace Lancaster, a 16-year-old girl living in Indianapolis Indiana with her two parents is experiencing cancer. The spread of this cancer that affects her thyroid and lungs, has been slowed with the use of a new drug. This cancer affects Hazel's ability to breathe and the doctors require she uses a portable oxygen tank.
Hazel struggles in her relationships with her parents and new-found, cancer surviving, friend Augustus. She avoids romantic relationship with Augustus because she doesn't want to break his heart when she eventually dies. Hazel fears being a "grenade" and pushes away her family because of that fear.
Hazel and Augustus travel to Amsterdam to meet Peter VanHouten, an author the teens have a shared love for, and writer of An Imperial Affliction. On the way to Amsterdam the pair quickly bonds and Hazel begins to fall for Augustus. Augustus's cancer returns, and it seems to be worse then it was before.
Hazel rushes to a gas station by the call of Augustus, only to find him distraught and in a terrible condition. His Cancer has spread over most of his body and he has become hopelessly infected. At this point, it has become obvious that Augustus's cancer is incurable.
Augustus's cancer overtakes him and he passes away. Even though this is heartbreaking, Hazel feels the relationship, and the sadness that came with it was worth it. After he passes, Hazel becomes shut off and isolated.
VanHouten comes to Augustus's funeral and apologizes to Hazel for how rude he was to her and Augustus. He then exposes to Hazel the reason he never finished his book. Hazel is also encouraged by the eulogy Augustus wrote for her, and she gets a sense of closure from it.