Awkward, lanky, and self-loathing, Greg Gaines (Thomas Mann) is a senior at Pittsburgh’s Schenley High School who appears to drift through life while only seeming to broadly associate himself with the various cliques within Schenley’s halls. He learns that a fellow student and former childhood friend of his, Rachel Kushner (Olivia Cooke), has been diagnosed with leukemia and is forced by his parents (Nick Offerman and Connie Britton) to befriend her in her time of need. Despite neither of them truly wanting the other’s company, Greg manages to strike up a conversation about her pillow collection. She finds his quirky personality endearing and they make plans to meet on a regular basis.
Over time, Greg introduces Rachel to his longtime co-worker Earl (RJ Cyler), with whom he makes short films parodying famous film titles. At Greg’s reluctance, Earl convinces Greg to share their collection of short films with her, which she finds entertaining. As Rachel begins chemotherapy, her disease worsens, and Greg begins spending less time at school and more time caring for her.
Discovering them shooting another film, Madison (Katherine C. Hughes), Greg’s crush, convinces Greg and Earl to make a film dedicated to Rachel, and Rachel persuades Greg to apply to a local college. Despite being accepted by the college, Greg continues to ignore schoolwork, and eventually school altogether, in order to finish the film. After realizing that her chemotherapy is doing more harm than good, Rachel opts to discontinue her treatment. Greg and Rachel have a heated argument over her choice where she points out his unwillingness to do anything selfless unless he’s told to do so. He leaves, devastated that he can no longer help her.
In a rage, Greg confronts Earl, blaming him for the events leading to the end of his friendship with Rachel, with Earl admonishing Greg’s inability to care and sympathize for anyone but himself despite the genuine affection she gave him. Afterward, Earl gives Greg a heartfelt testimonial for Rachel before letting him know that he’s finished with their friendship. Greg is also told that due to his failing grades, he has been rejected by the college he thought he would attend.