Professor Lola Sánchez investigates the truth behind the events experienced by Rafael Sánchez Mazas, one of the founders of the Falange Española party, during the Spanish Civil War.

Since childhood, Luisa and Miguel have always been good friends; but several years later, as adults, when Spain faces the abyss of the Civil War (1936-1939), they support ideologically opposed camps.

Javier Navarro, a Falangist, is ordered to infiltrate Republican Madrid to deliver a message to a member of the Fifth Column.