La Frontera - Season 1

1987. Mario Sanz, a Civil Guard captain stationed in the Basque Country, learns from an informant of plans by a dissident ETA group to attack Paris. This action goes against the organization's leadership, which intends to force France to reconsider its recent collaboration with Spain in the fight against terrorism.

Mario is ordered to forget about the Paris attack. The Ministry of the Interior prefers to look the other way: to let France know what ETA really is. Mario is about to have a twisted mind, but he makes a bold decision: go to Paris at his own risk and reveal what he knows to Léon Renaud, his contact in the French police.

With Mario already in Paris, Izaskun Bergara, the girl he's just started dating, unexpectedly shows up at his hotel. What Mario doesn't know is that she's the daughter of a long-time ETA leader. He's been tasked with getting close to him and keeping an eye on him... and perhaps, when the time comes, eliminating him. But now they must join forces in an unnatural alliance to prevent the attack.

Mario's informant discovers the identity of one of the dissident ETA members. Meanwhile, the captain and Izaskun risk their lives to obtain information from the Marseille mafia, who are about to sell explosives to the terrorists, believing them to be bank robbers. The only possible course of action is to allow the surrender, follow the ETA members, and dismantle the commando before they act.

The terrorists' pursuit fails: they now have the explosives, and their plan continues. But Léon and Mario's investigation also continues, and they manage to locate the terrorists' safe house... even though they are no longer there. The attack is imminent. Can they prevent it?