Giulio, seriously injured in Armido's ambush, manages to escape and is helped by a kid , Paolino, who hid him in a hut on the beach. Giulio fights against death for long days.
In Rome Cardinal Colonna needs money to go on with his invasion of the city. Prince Savelli's offer can't be refused. In exchange of a great amount Colonna will find Giulio Branciforte, dead or alive, and his corpse must be shown to Elena, so that the girl may finally accept to marry the old prince.
Elena goes on hoping Giulio is still alive somewhere and rejects her mother pressure for a marriage with Savelli. Her sureness is shattered when she is shown...
... the corpse of a young man wearing the half of the necklace Giulio used to wear. She is desperate because she doesn't know that necklace was found by Armido on the beach and put around another man's neck.
The corpse is unrecognizable.
When Prince Savelli is rejected even after the "certainty" of Giulio's death, he decides to revenge. He denounces Elena to the Inquisition Tribunal for her sinful behaviour.
In prison Elena meets Lisetta - whom she doesn't know - who is accused of murdering a nun and who hates her deeply because she's always been in love with Giulio.
Meanwhile Giulio is safe and has joined his friends Ugone and Ferdinando with the help of Paolino. He discovers Elena is in prison and wants to save her. But ...
... someone else has helped her to escape religious justice: Prince Savelli. She has decided to marry him.
Actually she only wants revenge on Prince Savelli because she knows he has plotted against Giulio and paid for his death. She wants to kill him on their wedding bed. Unfortunately, the old prince is stronger than her ...
His rage is irrepressible and terrible, his revenge devilish.
He orders Elena to be walled up, he wants to leave her starve there.
Meanwhile, Giulio, Ugone and Ferdinando hear that Lisetta is going to be executed publicly. Giulio asks Colonna the permission to go to Rome and try to help her his old friend and ex-lover.
Once there he can only listened to Lisetta's confession: she has betrayed him and his friends more than once; she has met Elena in prison and treated her very badly. All this because of her blind foolish jealousy. She asks him for forgiveness before dying.
Giulio discovers the old cardinal, whom he considers like a father, was part of Elena's mother's and Prince Savelli's plot against him; Cardinal Colonna convinced Elena that he was dead and she decided to revenge Giulio's death.
Under Giulio's threat, the cardinal confesses that he knows something has happened between the old prince and his new young wife: she has disappeared.
Giulio gets to Rome just when it is under attack and being sacked.
Prince Savelli is killed and dies without revealing where he has hidden Giulio's beloved Elena.
Luckily, Giulio finds her just in time. The two lovers wait for the soldiers' leaving and finally they are totally free...
... to live their love story without any further interference. They join Donna Vittoria Colonna who has been waiting for them in Ischia.
Read the original novella by Stendhal, THE ABBESS OF CASTRO, on line
but remember the TV series is very loosely based on it!