Hazel Grace Lancaster, a 16-year-old with thyroid cancer that has spread to her lungs, attends a cancer patient support group at her mother's behest. At one meeting, Hazel meets a 17-year-old boy currently in remission named Augustus Waters, whose osteosarcoma caused him to lose his right leg. Augustus is at the meeting to support Isaac, his friend who has eye cancer. Hazel and Augustus strike a bond immediately and agree to read each other's favorite novels. Augustus gives Hazel The Price of Dawn, and Hazel recommends An Imperial Affliction, a novel about a cancer-stricken girl named Anna that parallels Hazel's own experience. After Augustus finishes reading her book, he is frustrated upon learning that the novel ends abruptly without a conclusion, as if Anna had died suddenly. Hazel explains the novel's author, Peter van Houten, retreated to Amsterdam following the novel's publication and has not been heard from since.
A week later, Augustus reveals to Hazel that he has tracked down Van Houten's assistant, Lidewij, and, through her, has managed to start an e-mail correspondence with Van Houten. The two write to Van Houten with questions regarding the novel's ending; he eventually replies, explaining that he can only answer Hazel's questions in person. At a picnic, Augustus surprises Hazel with tickets to Amsterdam to meet Van Houten, acquired through the story's version of the Make-A-Wish Foundation, "The Genie Foundation".
Upon meeting Van Houten, Hazel and Augustus are shocked to discover that he is a mean-spirited alcoholic. Horrified by Van Houten's hostile behavior towards the teenagers, Lidewij confesses to having arranged the meeting on his behalf. Lidewij resigns as Van Houten's assistant and takes Hazel and Augustus to the Anne Frank House, where Augustus and Hazel share their first kiss. Later that night Hazel and Augustus partly lose their virginity to one another in Augustus's hotel room, confessing their mutual love for each other.
The next day, Augustus reveals that his cancer has returned. Upon their return to Indianapolis, Augustus's health continues to deteriorate, resulting in him staying in the ICU for a few days. Fearing his death, Augustus invites Isaac and Hazel to his pre-funeral, where they give eulogies. Augustus dies soon after, leaving Hazel heartbroken. Van Houten shows up at Augustus's funeral to apologize to Hazel.
Hazel learns that Augustus had written an obituary for her, and reads it after Lidewij discovers it amidst Van Houten's letters. It states that getting hurt in this world is unavoidable, but we do get to choose whom we allow to hurt us, and that he is happy with his choice, and hopes she likes hers too. The book closes with Hazel stating that she is happy with her choice.
