Twenty-eight-year-old Isma Pasha is detained at Heathrow Airport, where she is held and interrogated for two hours, singled out specifically for her hijab and her Muslim background even though she is a British citizen. After officers question her on whether she considers herself British, she is allowed to board the plane to Boston, where she will be pursuing a PhD in sociology under an old professor of hers, Hira Shah.
Isma spends her days working and reading in a coffee shop, where she befriends 24-year-old Eamonn Lone, who is also from London. Isma recognizes Eamonn as the son of Karamat Lone, a British politician who, though he is Muslim and has a Pakistani background, has largely made British Muslims feel like he has turned his back on them in order to gain support of the wider British public. Eamonn and Isma become friends over the next few weeks, and Isma grows romantically interested in Eamonn as well, even though Isma quickly realizes that Eamonn has little understanding of his Muslim or Pakistani heritage. When Karamat is appointed Home Secretary of the U.K., Isma admits that she knows who Eammon’s father is, and that she is critical of his treatment of his Muslim constituents. As a person who looks up to his father a great deal, Eamonn grows cold toward her as a result.
That night, Isma is woken by a call from her 19-year-old sister, Aneeka, who is extremely upset after finding out that Isma was the one to report their brother, Parvaiz, to the police. Aneeka feels completely betrayed, even though Isma assures her that the police would have found out about what Parvaiz had done anyway and that she was trying to protect Aneeka. Aneeka says that Isma has made Parvaiz unable to come home, and she tells Isma not to contact her anymore. Upset, Isma texts Eamonn, wanting comfort and to explain her perspective more fully. Isma tells him that her father, Adil, left her family to become a jihadi in Bosnia. He was imprisoned in Bagram and then died while being transported to Guantánamo. When her family tried to approach Karamat, a new Member of Parliament at the time, to find out more information about Adil’s death, Karamat said that they were “better off without him.” In the present, Eamonn apologizes to Isma, but he still defends his father’s actions. As they part, Eamonn tells Isma that he is returning to London and offers to deliver M&Ms that Isma was planning to send to Aunty Naseem, a neighbor with whom Aneeka is currently staying.
Back in London, Eamonn delivers the M&Ms to Aunty Naseem and meets Aneeka, who is instantly suspicious of him because of his father. But when he leaves, Aneeka follows him and asks him to take her to his apartment. Eamonn does so, and when they arrive, Aneeka takes off her hijab and the two have sex. The next morning, Aneeka tells him that she wants to keep their relationship a secret, and he agrees. This also means that Aneeka will not give Eamonn her cell phone number, nor can he find her online.
A few weeks pass, and their relationship deepens, though occasionally they also butt heads over Karamat’s attitudes towards Muslims. Eamonn gives her keys to his apartment, and they get to know each other better. Eamonn is amazed at the fact that Aneeka can be so devoted in her prayer and yet still have so much control over and freedom in her own sexuality. Eamonn even suggests to Aneeka that he wants to propose to her. Aneeka then admits to Eamonn that her twin brother Parvaiz left to go to Raqqa, Syria, the previous year, to join ISIS’s media unit. At first Eamonn is extremely hurt, particularly after realizing that this is why she pursued him in the first place, but Aneeka assures Eamonn that she truly loves him, and that she just wants to get her brother home.
Eamonn approaches his father, telling him about Aneeka and then about Parvaiz. Karamat immediately grows furious with how Eamonn has been completely blinded by Aneeka, and he tells Eamonn that he cannot see Aneeka again.
The perspective then shifts to Parvaiz, hopping between the present and the events that led to his leaving for ISIS. The previous fall, he was approached by a man named Farooq, who told him that he had heard stories of heroism about Adil. Parvaiz eagerly listens to Farooq, excited to hear about his father as a hero rather than as a “feckless husband,” as his mother, Zainab, and grandmother always told him before their deaths when he and Aneeka were 12 years old. Farooq teaches him about the conflict between Islam and Christianity, and he often talks about how to be a man. One day, Farooq invites Parvaiz over to his flat, and two cousins chain Parvaiz to the floor in a squatting position for hours before waterboarding him. Parvaiz is at first horrified, but then he realizes that this torture makes him feel connected to his father for the first time, and so he asks to be tortured again. Over time, Farooq convinces Parvaiz to come to Syria with him to find more people who knew his father.
Parvaiz creates a cover story about getting a job on a popular music show in Pakistan, then leaves for Syria. When he arrives, Farooq takes his passport and leaves for the front lines before Parvaiz realizes how little information he’s been given. He undergoes months of training, then joins the media unit of ISIS. He also learns that Aneeka and Isma know where he has gone, and that MI5 is now monitoring them. Parvaiz recognizes that he has become like his father only in his “abandonment of a family who had always deserved better than him.” Parvaiz is taken out for a field recording, but when he realizes this means filming an execution, he grows queasy and cannot watch. In another incident, Parvaiz sees a woman pinned underneath a wall that has been bombed, but because she is not wearing a face veil, he is not allowed to approach her even as she begs for help. This is a turning point, as he realizes the horrible mistake he has made. He calls Aneeka, who tells him to get to Istanbul, Turkey, to go to the British consulate.
A few weeks later, he and Farooq take a trip to Istanbul to pick up new recruits and to buy media equipment. When Farooq leaves Parvaiz alone in the electronics store, Parvaiz runs out and takes a cab to try to get to the British consulate. He calls Aneeka, who says that she will fly to Turkey and tells him to wait for her. He also receives a text from Farooq, implying that Farooq is coming after him. Realizing that it is unlikely that they will let Aneeka onto a plane, he approaches the British consulate alone, desperate to get home. Before he steps inside, he is shot and killed by Farooq.
Aneeka is overwhelmed with grief after learning of Parvaiz’s death, and she refuses to be comforted by Isma, who flies home immediately. They watch stories mount about Parvaiz, calling him “the latest name in the string of Muslims from Britain who have joined ISIS.” The news then shows a clip of Karamat, who says that he has revoked the citizenship of all dual nationals who have left Britain to “join our enemies.” He says that Parvaiz’s British citizenship has been revoked and that he will be buried in Pakistan. Policemen then come to interview Aneeka about her relationship with Eamonn. She admits she pursued him because she thought he could help get her brother home. Isma is appalled to learn of the relationship and the reason for it. Despite Isma’s attempts to reconcile with Aneeka, Aneeka refuses to be comforted because she believes that Isma is the reason that Parvaiz could not come home and is now dead.
More articles come out about the story: one quotes Isma, who says that she and Aneeka were shocked and horrified to learn that Parvaiz had joined ISIS, and that she immediately informed the Counter Terrorism Command. Another article centers on the fact that Parvaiz’s father also fought with jihadi groups. A third article comes out, explaining that Karamat’s office revealed Aneeka and Eamonn’s affair in the name of transparency. The article describes Aneeka as Parvaiz’s accomplice, having hunted down Eamonn to try and convince Karamat to return her brother to Britain. Meanwhile, Aneeka applies for a Pakistani passport and goes to Karachi to retrieve Parvaiz’s body.
The story shifts perspective once more, to Karamat. Eamonn, who is now staying with friends, calls Karamat and tells him that his actions do not look good from the outside. Eamonn continues to try to talk through the politics, but Karamat dismisses him, telling him not to try to “develop a spine,” and he also denigrates Aneeka. After the call, Karamat watches the Pakistani news, and he sees that Parvaiz’s body is delivered to a park near the British Deputy High Commission, where Aneeka is holding vigil. She implores Karamat and the Prime Minister for justice. The Prime Minister and Karamat refuse to allow Parvaiz’s body to return, a decision which is supported by Parliament.
The next morning, Eamonn arrives in Pakistan. Eamonn has also released a video, criticizing Karamat’s decision and supporting Aneeka, whom he describes as his fiancée. He says that Karamat’s actions are due to his own “personal animus”—a phrase which deeply hurts Karamat. Articles are released in the morning papers, painting Karamat as an ambitious son of immigrants who married into wealth, used his identity as a Muslim to win elections, and then left it behind when it was no longer valuable.
Karamat returns home to be with his wife, Terry, and his daughter, Emily. After talking through the situation with Terry, he comes to the realization that he should allow Aneeka to bring Parvaiz’s body back to Britain. Soon after, his security detail receives word of a threat. Karamat, Terry, and Emily are taken to the safe room in his house, then released when they find out that the threat wasn’t intended for them.
In Pakistan, news outlets capture Eamonn’s arrival in the park. When he approaches Aneeka, two men run up to him and lock a belt of explosives around his waist. Everyone else starts to flee, but Aneeka approaches him and holds him. For a moment they are “two lovers in a park, […] at peace.”
