We are in 1620 and Castell’Arquato is ruled by Cardinal Francesco Sforza who oppresses the population with a harsh government, burdening it with numerous and onerous taxes.
The revolt is getting closer and closer, the inhabitants of the village are waiting for the right occasion and the Cardinal is waiting to find a scapegoat and intervene to restore order. It is at this point that Sergio Montale enters the scene, a knight recently arrived in Castell’Arquato and accompanied by his servant, Antonio Galanti called Spadone for his ability to handle weapons.
Someone accuses the young man of conspiracy, the rumor reaches the Cardinal and it is enough for an accusation of high treason.
Sergio and Antonio are locked up in the prison of the Rocca and in vain they try to make them confess a non-existent guilt and it is decided to execute them.
Here appears Laura, daughter of Gaspare Della Vigna, head of the guards, who falls in love with the young Sergio and on the night of April 15th, eve of his execution, she manages to make the condemned escape. Perhaps the escape would have been successful, but at this point another character, Giacomo Manaro, already Della Vigna’s helper, shows up and immediately notices the fact and raises the alarm.
For him, who has always been in love with Laura, it is the good occasion to take revenge for the refusals received. He also takes advantage of it to kill his superior, of whom he wanted to take the place, throwing him off the drawbridge.
Laura hears her father’s scream and wants to go back to help him, but in the meantime the guards arrive and capture Sergio.
The Manaro warns the Cardinal of the incident accusing Sergio of having killed Della Vigna, and asks for death for him and for Laura.
On May 20 the two unfortunate lovers are beheaded. It seems that the matter has been resolved with honor of the Manaro. In reality, Antonio, the faithful squire, is still alive, and some months later, he manages to enter the Rocca, reach his master’s murderer and stab him. He then immediately turns himself in to the Podestà, who orders a trial.
The Cardinal would like his death, but the expenses for the execution, those of the executioner and the notary, are too expensive for the empty coffers of the village. It is therefore decided to sentence him to life imprisonment. The poor man will end his life in the prison of the Rocca, which is located inside the mighty dungeon. After him many others will have the same fate.