In the aftermath of the 13 November 2015 attacks in Paris, the DGSE and DGSI must join forces. While Lucie interrogates a repentant prisoner, Vincent focuses on a man who has come to announce his brother's departure for Syria.

French secret service agents are working tirelessly to locate the perpetrators of a terrorist attack, under immense pressure to prevent their recurrence.

Thanks to Ulysse's cyber-infiltration, Lucie and her team are finally able to identify terrorists planning to carry out an attack in France. Malika decides to return to Syria to mobilise Yassine.

The leads followed by Lucie and her team are not bearing fruit. Weakened by the Coalition's strikes, the Islamic State is suspected of preparing its last stand, a double attack on French soil.