Government oppression.
The main theme of the novel is the excruciating tyranny of Iranian leadership, especially in the 1970's. The SAVAK secret service operates like the Gestapo in Nazi Germany, arresting and executing anyone who is willing to publicly disagree with the government's decisions.
A valuable member of their community is lost when SAVAK finds Doctor and kills him. Then, Zari is killed (we think). The main boys, Pasha and Ahmed, are each separately mistreated by the government, in different ways. The point is that no one survives political injustice unscathed. It's almost as if the Iranian government was specifically executing its law in a way that made everyone paranoid and terrified of them.
Coming of age.
The other part of this book that is worth mentioning is that technically, it's a coming-of-age story, since the novel's main characters start out as high school kids hanging out on the roof, pleasantly unaware of the political turmoil of their state. Then, by the end, they are all activists, taking a responsible stance against the government, in their limited, sometimes immature way. In any case, the sobering events of the novel force the kids to grow up, and by the end, Ahmed is even married.
Trauma, tragedy, and loss.
In this story, two innocent, young guys are brutally treated for their association to Doctor, an enemy of Iran's tyrannical state. Ahmed is beaten and released, and Pasha is institutionalized, drugged (the reader suspects), and then released, but now with a tenuous grasp on reality.
The trauma of Doctor's death, coupled with the unbelievable fate of Zari at her own hands, seems to have pushed Pasha to the brink of insanity. Then, Soraya (potentially Zari in disguise, or else, she's lying to Pasha because she is scared of his manic episode) allows Pasha to say goodbye to Zari, claiming that when he returns from America, she will be waiting. But the reader understands that Zari died, burning herself to death. In all these ways, the theme shines through: Because of the political state, each of the characters ends up deeply traumatized by the tyrannical authority of the government, and every character suffers serious tragedy as a result.
