The following version of the book was used to create this study guide: Mafi, Tahereh. A Very Large Expanse of Sea. Harper Collins, New York, New York, 2018. Kindle AZW file.

Shirin is a 16-year-old girl who lives with her parents and older brother Navid. Her parents are Persian, meaning Shirin has dark skin. She chooses to wear a hajib, feeling it is her right to keep her hair “just for myself” rather than putting it on display. The story takes place just months after the 9/11 attack on America, at a time when many Americans are fearful of anyone of Middle Eastern descent. Shirin's parents move often, meaning Shirin has never had the opportunity to make friends who can see past her ethnicity and the hajib. With this background, she begins her sophomore year at yet another high school among a largely white student body. Shirin's past experiences make her decide to keep to herself this year, focusing on just getting through high school in the hope that college will be better.

Shirin meets Ocean in her biology class. He seems nice, but she is not interested in opening herself up to any relationship. Ocean soon makes it clear he wants more than just friendship in spite of Shirin's continued reluctance. One day he convinces her to go to his car. They kiss without realizing the number of people who are watching. Shirin's predictions come true to a greater degree than she imagined because Ocean is the star of the varsity basketball team. Shirin is attracted to Ocean but feels sure the relationship cannot endure. While Shirin is trying to create distance between them, Ocean becomes committed. When he convinces Shirin to ride to school with him one morning, a student throws a cinnamon roll at Shirin, hitting her in the face. When she goes to the bathroom to wash it off, a girl takes a photo of Shirin without her hajib and circulates it around school. Another student circulates an email to students, teachers, and parents, accusing Ocean of supporting terrorism. With Ocean's position on the basketball team in jeopardy, Shirin is ready to break off the relationship. When Ocean's mother tells Shirin that Ocean's only hope of a good college is a basketball scholarship, Shirin does break up with him. When Ocean discovers why, he hits his coach and quits basketball for good.

The only positive thing in Shirin's life at this point is a breakdancing club founded by her brother Navid. Three of Navid's friends are also involved, and the daily practice helps Shirin focus on something other than her broken heart. The group wins a talent show, and Shirin is shocked to discover that her status at the school has gone from potential terrorist to popular and accepted. In this new situation, Shirin and Ocean make up and become an accepted couple. The relationship is not able to endure, however, because Shirin's parents move again at the end of the school year. In the final text as Shirin is leaving, Ocean begs Shirin to remember him always. She does.