Life is hard enough for teenage Darius, but things get even worse on the day that bully Trent Bolger and his fellow Soulless Minion of Orthodoxy, Chip Cusumano, steal Darius’s bike’s wheels and seat while he’s at work. Trent and Chip replace the bike seat with rubber testicles that people sometimes hang from trailer hitches. Darius has to call Dad to come pick him up from work at The Tea Haven. As usual, Dad suggests that Trent would stop bullying Darius if Darius only stood up for himself. Clearly, Dad has never been bullied—he’s a Teutonic Übermensch, a highly successful, Audi driving, perfect architect.
After dinner, Darius and Dad go to the living room for their evening ritual: watching one episode of Star Trek, which is the only time they can be a “real father and son.” Midway through the episode, Mom accepts a video call from her parents in Iran, Mamou and Babou. Darius and Dad briefly say hello, finish their episode, and then go to the kitchen to take their medications—they both take medication for depression. Dad shares with Darius that Babou, who has a brain tumor, isn’t going to get better. The family is going to visit Iran and they’ll be there over Nowruz, the Persian new year.
A few weeks later, Darius carries his sleepy younger sister, Laleh, through the airports and tries to ignore Dad when Dad polices what Darius eats (Darius is overweight because of his medication, not because he lacks self-control). Darius is also resentful because Chip broke Darius’s backpack yesterday, so he has to use a messenger bag of Dad’s as his carry-on bag (he hates messenger bags). The family lands in Tehran just before sunrise. After a frightening interrogation with a customs officer, Darius and his family are greeted by Mamou and Dayi Jamsheed, one of Darius’s uncles. They drive the few hours to Yazd, and—after a shower—Darius promptly falls asleep.
Darius wakes to a human-shaped shadow crossing outside his window. When he goes outside, Babou has just climbed onto the roof to water his fig trees while a boy about Darius’s age, Sohrab, passes him the hose from the courtyard. Babou certainly doesn’t look sick, and he tells Darius and Sohrab to be friends. As Sohrab takes Darius to his uncle Agha Rezaei’s store to buy something for Mamou, he explains that he and his family are Bahá’í. He also invites Darius to play soccer tomorrow with some of his friends, and Darius accepts. The next day, Darius braves a public locker room with no stalls to change into borrowed soccer gear and shower after—and Sohrab and his friends, Ali-Reza and Hossein, tease Darius for being uncircumcised, calling him “Ayatollah Darioush.” Later that afternoon, Sohrab comes to Mamou’s house to apologize. He admits he only bullied Darius because it was nice to not be Ali-Reza’s target for once; Ali-Reza is very prejudiced against Bahá’ís. Darius accepts his apology, and somehow he knows he and Sohrab will be friends forever.
The next day, Sohrab joins Darius’s family on their trip to the ruins of Persepolis. There, Darius sees carvings of his namesake, Darioush the Great—but he doesn’t feel great and brave like Darioush. Babou drives, but on the way home, he gets angry and pulls over. Dad finishes the drive and Sohrab whispers to Darius what happened: Babou got lost. He won’t be able to drive again after this.
It’s Nowruz a few days later. Darius starts the day feeling secure in his identity and in his place in his family. He feels even better when Sohrab gifts him a soccer jersey for the Iranian national team. But his uncle Dayi Soheil calls Darius fat, and Dayi Jamsheed suggests Darius isn’t very Persian since he doesn’t like cucumbers. Even Dad seems to fit in better than Darius, since he plays Rook with Babou and Darius’s uncles. Darius and Sohrab sit in the garden, talking about Darius’s fraught relationship with Dad and how Darius doesn’t feel like he fits in. Sohrab also reveals that he’s here with only his mom, Khanum Rezaei, because Sohrab’s dad was wrongfully arrested and imprisoned years ago, just for being Bahá’í. He’s now in solitary confinement in a Tehran prison, and Sohrab worries he won’t see his dad again.
On the day after Nowruz, it’s traditional to visit friends. So, Darius goes to visit Sohrab. Sohrab introduces Darius to his favorite food: romaine lettuce leaves dipped in mint syrup, which Babou used to make until his brain tumor made that difficult. They then go to a park to sit on top of a squat public restroom and stare out at the city. That night, though Dad brought Star Trek on his iPad so he and Darius can continue their tradition, Dad insists on letting Laleh watch with them. It’s obvious to Darius that Dad loves Laleh better.
Early the next morning, Darius and his family visit the Towers of Silence, where Zoroastrians used to bury their dead until sky burials were outlawed. When they get back, Darius and Sohrab take Laleh to get ice cream at Agha Rezaei’s store. Laleh is fluent in Farsi, and she chatters at Sohrab in Farsi, which Darius doesn’t speak. Sohrab asks her to speak English so Darius can understand.
Over the next week, Sohrab joins Darius’s family to visit Dowlatabad, a palace and gardens, and invites Darius to play soccer again with Ali-Reza and Hossein. Though the boys continue to call Darius “Ayatollah,” Sohrab tells the younger boys they’re playing with that this is because Darius is in charge—and Sohrab and Darius shower after the other boys are finished and have already left. They play daily for the rest of the week, and then Sohrab and his mom join Darius and his family for chelo kabob, a huge treat, at the end of the week. After the meal is over, Sohrab and two of Darius’s older cousins, Parviz and Navid, teach Darius to play Rook. Darius is terrible at it, but he has fun.
Babou insists on taking everyone to the Atashkadeh, the Zoroastrian fire temple, the next day. But when the family arrives, Babou isn’t feeling well, so he and Mamou stay in the car. It’s a sobering experience for Darius, as he thinks about Babou’s mortality while staring at the ceremonial flames that have been burning for about 1,500 years. When the family gets home, Darius finds Mom looking at photo albums. She shows him a photo of Dad holding baby Darius, which makes them both sad: if only Dad and Darius could act like father and son, and if only it was easy like it seems in the photo.
The next morning, Darius wraps a pair of cleats he bought as a going-away present for Sohrab to replace Sohrab’s two pairs, which are falling apart. But when Darius gets to the Rezaeis’ house, Sohrab and his family members are distraught—Sohrab’s dad was killed in prison. Wild with grief and anger, Sohrab tells Darius to go away and that nobody wants him. Darius believes Sohrab and runs to the public restroom roof, where he sits for hours and cries.
Dad finally finds Darius and joins him on the roof. He tells Darius not to cry, which makes Darius cry more—Dad, he snaps, just wants Darius to never feel emotions and to be perfect. Soberly, Dad shares that he’s just trying to protect Darius from depression’s dangerous effects. He reveals that just before Laleh was born, Dad’s meds stopped working and he spent a few months taking heavy tranquilizers so he wouldn’t hurt himself. Dad admits he fears the same thing happening to Darius, and he feels awful for passing depression on to his son.
It’s Darius’s birthday the next day. While everyone else visits the Rezaeis, Dad and Darius wander around Yazd together and then rejoin the family for Darius’s birthday dinner. Darius packs his suitcase, including the soccer jersey from Sohrab, his “Persian camouflage”—which Darius loves, but which maybe turns him into someone he isn’t. Late that night, Sohrab stops by to apologize and to thank Darius for the shoes. The boys go to the bathroom to stare out at the city and sit in companionable silence. They return to Mamou’s house and say goodbye, and Darius knows he and Sohrab will stay friends. In the morning, Darius bids Mamou and Babou goodbye and gets into Dayi Jamsheed’s SUV for the ride to the airport.
Darius spends two days recovering before he finally returns to school. He uses Dad’s messenger bag rather than get a new backpack; it feels better these days. His gym class is playing soccer and the teacher, Coach Fortes, is impressed with Darius’s skills, which have improved since he spent so much time playing soccer in Iran. Coach Fortes suggests Darius try out for the school team in the fall, and Darius agrees to think about it—it’d be fun to tell Sohrab about playing on a team in one of their almost-daily emails. It also surprises Darius when Chip apologizes for helping Trent destroy Darius’s bike, and when Chip reveals he knows that Darius’s namesake is Darius the Great. That evening, Dad and Darius watch Star Trek and then sit down for tea in the kitchen, which is their new tradition. Darius finally feels okay.