During a routine operation, the Spanish police stop the world's most wanted terrorist; this puts Spain in the spotlight of jihadist terrorism.

The lack of resources and the pressure to catch terrorists increases tensions within the unit, whose members also have to deal with the personal problems that come with their exhaustive dedication to police work.

The disappearance of an infiltrated agent in the terrorist cell triggers all the alarms; the unit investigates the surroundings of the arrested terrorist leader to detect the connections and next steps of the terrorist cell that threatens Spain.

The terrorists receive support; the unit suffers some setbacks that compromise their police work but that help them unite its members.

Sala Al Gareb commits suicide inside the isolated prison cell where he has been confined; as far as Carla's bosses are concerned, his death means the end of a complex and uncomfortable situation.

The men and women from the unit feel demoralized, deeply grieved and frustrated by their inability to prevent the terrorist attack in Madrid, but the investigation must continue.