Following the death of Nawal Marwan, a Canadian immigrant, her two children, fraternal twins Jeanne and Simon, meet with French Canadian notary Jean Lebel, a friend of their mother. Nawal’s will makes reference to not keeping a promise, denying her a proper gravestone and casket, unless Jeanne and Simon track down their mysterious brother, whose existence they were previously unaware of, and their father, whom they believed was dead.
A series of flashbacks reveal Nawal came from a Christian Arab family in an unnamed Middle Eastern country, and that she fell in love with a Palestinian refugee, resulting in her pregnancy. Her family murders her lover and nearly shoots her as an honour killing, but her grandmother spares her, tattoos the baby and abandons him, and sends Nawal to the fictional city of Daresh. While at school, a civil war and war crimes break out as Christian nationalists attack Muslims and refugees, with Nawal opposing the war on human rights grounds. Her son’s orphanage in Kfar Khout is destroyed by the nationalists, and unknown to her, her son has been rescued by a Muslim warlord, Chamseddine, who converts him into an Islamic child soldier. Seeking revenge for the loss of her son, Nawal joins the Muslim fighters and shoots a nationalist leader. Afterwards, she is imprisoned in Kfar Ryat and raped by torturer Abou Tareq. She consequently gives birth to the twins.
After travelling to her mother’s native country, Jeanne uncovers this past, and persuades Simon, who is angry with his mother’s unusual personality, to join her. With help from Lebel, they learn their brother’s name is Nihad of May and track down Chamseddine. Simon meets with him personally, and he reveals the war-mad Nihad was captured by the nationalists, joined their army, and took the name Abou Tareq, making him both the twins’ half-brother and father. Nihad had immigrated to Canada and Nawal only learned his true identity after recognizing him at a Canadian swimming pool and seeing his tattoo. The twins find Nihad in Canada and deliver Nawal’s letters to him without speaking to him. Nawal gets a gravestone, which Nihad visits.