العدو المجهول

The regent of Mexico City, Corona del Rosal, wants to weaken his main adversary in the presidential succession by getting rid of the National Security Directorate. Meanwhile, Major Barrientos, the DNS leader, tries to strengthen its position.

The students' voice becomes louder despite their lack of organisation. But after the death of one of the student leaders and with the assistance of Barrientos, the students will finally become a more cohesive force.

The student movement becomes stronger as they establish the National Strike Council. With help from one of Barrientos' infiltrators, they organise and carry out the largest civil march ever seen, with over 150,000 participants.

Barrientos infiltrates guns among the students to make them seem like a more threatening force to President Diaz Ordaz. Meanwhile, the CIA tries to influence the military leaders of the country to move forward with a coup and they reject their plans.

President Ordaz arranges a meeting with the students through the Chief of the Presidential Office; the meeting appears to be a success, but Barrientos wants to discredit the gains attained during the meeting by creating a sense of "chaos."

Corona del Rosal convinces the president to use moles during the March of Silence, a march organised by the National Strike Council, in order to put an end to the organisation; Barrientos wants to thwart his plans by provoking a fight.