A young Parisian couple are embarking on fertility treatment when the man, Antoine, becomes convinced he saw his sister in news footage from Syria. The same sister who supposedly died two years before. He makes a rash decision.

Three childhood friends from London, Iyad, Paul and Nasser enter the fray. Antoine finds himself in the middle of a fire fight and recalls the aftermath of his Anna's passing. A dedicated Kurdish YPJ soldier, Sarya, is sent on a new mission.

Antoine manages to prove the veracity of his story. Ryan, a volunteer enlisted soldier, confirms the existence in the ranks of the YPJ of a Frenchwoman who could be his sister. Hoping to find the one who now calls herself Shamaran, Antoine convinces Sarya to let him follow a new mission led by the Kurdish battalion. Meanwhile, Nasser, Iyad and Paul, the three English jihadists, integrate into the army of the Islamic State. But the motivations of one of them seem murky .

Paris, six years earlier. Antoine, a student, lives in a shared apartment with Anna. The two follow one after the other, until the day Anna falls in love with Najib, an Iranian refugee... Back to the present. While in his memory the beginnings of the disappearance of his sister return, Antoine takes part in the life of the battalion and gets closer to Sarya. On the jihadist side, the offensive continues, and Nasser takes on a grueling mission. Antoine will soon cross paths with another Kurdish battalion, which may include his sister.

Flashback to Sarya's youth: the young woman lived in Paris for twelve years. After her mother's passing, she reluctantly returned to Kurdistan, at her father's request, but eventually got used to this new life. Back to the present. Sarya and her battalion are ordered to scout. Antoine sets off in pursuit of them and climbs into their truck without asking their opinion. In Raqqa, Nasser is not recovering from beheading a inactive person. But the video was very successful on the Internet. Paul learns that brothers in Birmingham are looking after his son and are going to send him to Syria.

A few years earlier, in Cairo. Anna then worked in the department of archeology and Egyptology at an American university and was soon to participate in excavations in Iran. During a party, she meets someone who will give her life an unexpected turn .

ISIS launches an assault on Kobani, causing hundreds of thousands of refugees to flee. As the Kurdish forces send their fighters to the besieged city, Antoine receives information that puts him face to face with his past and present choices. Iyad and Paul have joined Raqqa Nasser, who has new responsibilities .

As the opposing forces finally come face to face, Antoine is faced with a painful dilemma. In the opposite camp, Paul asks Nasser for an explanation after discovering spy equipment in his Koran.