Nadia refuses to betray her country, and is angry at Lefevbre's revelations. Ill from the stress of her situation, she confesses to Nadim, and is flown back to Syria. The Russian FSB confronts DGSE and buys its silence. In Algeria, DGSE fails to plant a bug on the General holding Cyclone; Cyclone is handed over to ISIS. Marina is trained to deal with interrogation by Marie-Jeanne, tested by an Iranian agent pretending to be Reza's wife, and offered the Iran secondment. In flashforward, Debailly continues to talk to the CIA; the Americans do not fully believe his story.

ISIS threatens to execute Cyclone; Debailly is asked to work on his rescue. Nadim tries to blackmail him with Nadia's life, wanting him to betray Syrian sources; Debailly refuses to do so. The Americans pull out of the Sahara operation; DGSE suspects they may have a mole. Marina is further tested before leaving for Iran. Debailly shares details of the rescue plan for Cyclone with his colleagues.

Debailly asks DGSE to help Nadia, but is refused. He attracts the CIA by approaching the Syrians, purporting to represent the Americans, and takes time off to meet the CIA (revealed as the flashforwards shown from Episode Two). Dr Balmes suggests his motivation is not love for Nadia, but craving for the double life he experienced undercover. He agrees to return to the DGSE as a CIA double agent. Meanwhile, Marina disappears in Tbilisi en route to Iran, kidnapped by the Georgian secret service to see from where she seeks help. Cyclone is rescued in an ambush near the border with Mali.

JJA, the director of Dsec, has taken over the leadership of Le Bureau, while Marie-Jeanne has moved to Egypt. A newspaper article on the events in Ukraine emerge. The agency fears they have a leak.

On his way to Riga, Sylvain disappears at Moscow airport. Marie-Jeanne is in the Sinai desert. She must work alongside the Egyptian agent Ramsès.

Malotru is in place in the Russian agency FSB as "Pavel Lebedev". Sisteron is sent in the greatest secrecy to Cairo. Meanwhile, Jules announces to JJA that he has located Sylvain's phone. Digital tracing indicates that Sylvain is in Phnom Penh, Cambodia.

Liz Bernstein and La Mule are quietly continuing their investigations to identify the mole in the service. After a few weeks of rest in Sologne, Marina finds her post in Paris. Sisteron is responsible for training Andrea on the computer programs used by Israeli hackers. Meanwhile, in Phnom Penh, Sylvain decided to collaborate with the group led by Véra. In Paris, his superiors questioned his ability to manage the danger associated with this mission.

A meeting between the different chiefs of the Sinai tribes is to be held at the Nile Sorman hotel where Marie-Jeanne is working undercover. Fouad, the Egyptian security officer, travels to Paris for a meeting with the Bureau. Marina joins Andrea in Jordan to help him in his mission.

At the DGSE, the work of JJA is carefully examined. Dsec is particularly interested in the way he manages Pacemaker, who is on a mission in Cambodia. In Cairo, Marie-Jeanne discovers that her hotel room has been bugged. Pacemaker is closely watched at work.

JJA is told to go ahead and recruit Mikhail. He contacts Pavel in Moscow to develop a strategy. Sylvain is sent to Seoul by the Russians to enlist Yellow Joon, a genius hacker. In Paris, Sisteron admits having lost confidence in JJA. In Cairo, intelligence indicates an attack is imminent.

Mikhaïl Karlov receives a parcel with the USB key which Sylvain uses at work. Both surprised and worried, he tries to reach the young hacker and learns that the young man is on a mission in Seoul. Meanwhile, Alexis Bakatine, the head of security at the FSB, is continuing his investigation into the spy "Black September" in order to find out if Pavel is a double agent.

Marie-Jeanne is back at the Bureau. Sisteron processes information from Karlov. Mikhail must explain to his wife and son the difficult situation they are in. Jonas discovers that the young woman with whom he has had an affair for several weeks is working ... for the Russians.

Marie-Jeanne presents her candidacy to succeed Michel Ponte as director of the service. An Uzbek tourist in Paris finds a weapon. Is he part of Mikhail's revenge?