In 1952, the Encarnación and Matilde Silva Montero sisters were murdered inside the tobacconist's shop they ran in the city of Seville.

The police soon arrested the three authors: Juan Vázquez, Antonio Pérez and Francisco Castro, being sentenced to death by garrote. The executioner, Bernardo Sánchez Bascuñana, coincides a few weeks after the execution with a friend of his, a retired civil guard, and tells him a terrible truth: the accused were innocent.

The civil guard decides to start an investigation on his behalf to find the real culprits of the double crime.