Inés (22), along with her husband Justo (28) and their best friend Gerardo (23), are members of Fatherland and Liberty, a violent paramilitary group with nationalist and neo-fascist ideological orientation that committed multiple terrorist acts with the purpose of overthrowing the left-wing government of the Popular Unity in the early 1970s. The title of the film refers to the emblem used by this group, which is commonly known as "The Spider" or "The Black Spider" in reference to the similarity between the logo and those arachnids.
In the midst of this struggle, they become embroiled in a risky and passionate love triangle. Together, they commit a political crime that changes the history of the country and, in the process, involves them in a great betrayal that separates them forever.
Forty years later, Gerardo reappears. He is not only driven by revenge, but also by his youthful obsession to revive the nationalist cause. The police catch him with a war arsenal in his house, and Inés, now a powerful and influential businesswoman, will do everything in her power to prevent Gerardo from revealing her past or that of her husband.