Facing Up tells the story of Dave Jacoby, a somewhat conservative teenager. Spanning the last few weeks of Dave's junior year in high school and the following summer, the story focuses on the relationship between Dave and his best friend, Jep. Considering his own overprotective parents, Dave envies Jep's independence and worldliness. Jep's parents are divorced and he lives in an apartment with his mother. Dave also envies Jep's girlfriend, Susan, a girl Dave has loved since seventh grade.
In the first part of the story, Susan tells Dave that she has outgrown Jep and is planning to break up with him. When Susan informs Dave that she now loves him, Dave is torn between his loyalty to Jep and his feelings for Susan. After witnessing Susan's shallowness, Dave decides that his friendship with Jep is too valuable to jeopardize. Before he can explain his actions to Jep, however, an accident on a rainslick road kills Jep and leaves Dave feeling responsible for Jep's death.
The latter part of the book describes Dave's attempts to cope with Jep's death. Finding it difficult to talk about his feelings with anyone, Dave shuts himself off from his friends and family. His only solace comes from his summer job, and he dreads the start of school in the fall. To appease his worried parents, Dave agrees to play football. Instead, however, he decides to go on a camping trip that he and Jep had planned the previous spring. Managing to dupe his parents into believing he will be attending football camp while they are on vacation, he takes off through the countryside on Jep's moped. Alone on the Long Island coast, Dave finally comes to terms with his loss. It takes a brush with drowning, however, to make him realize that he really wants to live.