One day at Support Group, Hazel meets a cute boy named Augustus who's missing part of his leg (from the dreaded cancer). Augustus is also friends with her friend Isaac, who is losing an eye (also thanks to cancer).
Augustus manages to get in touch with Peter Van Houten, the author of An Imperial Affliction and gives Hazel his email address.
Hazel promptly emails him and gets an invitation to come to Amsterdam, where he will reveal all the secrets about her favorite book. Wow-ee.
Unfortunately, Hazel gets ill and lands herself in the ICU. But after she heals, her doctor says it's a-okay to travel and she, her mother, and Augustus head off to Amsterdam together.
On the plane, Augustus proclaims to Hazel that he is in love with her.
They meet Van Houten, who turns out to be a drunken jerk and refuses to answer Hazel's questions.
At the Anne Frank House, Hazel and Augustus finally kiss. Back at the hotel, they promptly lose their virginities.
The next day, though, Augustus breaks some devastating news to Hazel: his cancer has returned and it's all over the place.
After Augustus dies, Hazel and her parents go to the funeral, his friend mentions to Hazel that Augustus was writing something for her.
Hazel learns that Van Houten had a daughter who died of cancer and tells him that he should go home, sober up, and write some more; but he keeps drinking.
Hazel receives an email from Van Houten's assistant that contains the eulogy Augustus had written for her.