1807 Mrs. Alberti, thirty-two-year-old widow, lives in Trieste with her young sister Antonia, a fragile, sad and thoughtful girl.
In this troubled time, when “laws have not yet entered into force,” and justice is often inactive, a gang of robbers, calling themselves “brothers of the common good”, is in the vicinity of the city. They are headed by a certain Jean Sbogar, endowed with a rumor of enormous growth and a "terrifying appearance." No one knows where he came from, but everyone agrees that he and his people are "ruthless and merciless."
Sisters often walk in the grove, where local peasants are usually going to sing and dance. During one of the walks, they hear a song about Jean Sbogar. The name of the villain makes them awe. Returning home at dusk, they meet a young man singing a song they have just heard. Sisters are embraced by vague forebodings.
Once on a walk, Anthony, swallowed by heat, sits down to rest under a tree and falls asleep. Awakening, she sees two men nearby. A young stranger tells his companion about his passionate and exalted love for Anthony. Attracted by the noise, Mrs. Alberti appears, and, like ghosts, the unknown disappear. Mrs. Alberti fears that one of Jean Sbogar's minions would fall in love with her sister. At the mention of the terrible robber Anthony is confused.
Antonia rarely leaves home. Only occasionally does she go to the shore of the bay to admire Duino Castle, which towers on a cliff, where, according to rumors, a gang of Jean Sbogar lives. Once at dusk she notices how two unidentified people board a boat and sail towards the castle. It seems to her that the voice of one of them belongs to a mysterious stranger who confessed his love for her. An inexplicable fear creeps into Anthony's soul.
Suddenly, the sisters have to go to Venice, and both joyfully hit the road. In an unfamiliar city, Antonia hopes to get rid of her worrying thoughts.
On the way, the sisters are asked to give a ride to a young monk from an Armenian monastery. They agree, and a young man in monastic vestments is seated in a carriage to them. A hat with large brim hides his face, but Mrs. Alberti manages to notice that his hands are "white and tender, like a girl's."
When the sisters pass by the castle of Duino, they are attacked by robbers. Suddenly, a young monk jumps out of the carriage, disperses the bandits and, having ordered the frightened coachman to go on, disappears. Anthony finds in this incident rich writing for his grim "dreamy reflections."
Arriving in Venice, both women immediately hear the story of a certain Lothario - a young man who is respected by all the inhabitants of the city, from the last beggar to an influential official and a prim aristocrat. The mysterious Aotario, endowed with many outstanding talents, does not make friends with anyone, helps the poor a lot and rarely happens in the same house twice. No one knows where he comes from, nor what is the origin of his truly fabulous wealth. Not only laws, but also love have no power over him.
At one of the receptions, Mrs. Alberti and Anthony meet the famous Lothario. Anthony is extremely excited. Lothario, possessing "extraordinary charm," shows interest in Antonia. When asked to sing, he sings a song about Jean Sbogar. It seems to Antonia that she already heard this voice somewhere.
Lothario makes a deep impression on Anthony. Gradually, communication with him becomes a need for her, and, not yet confessing to herself, she falls in love with this mysterious, always sad, but domineering young man. Despite the secret enveloping Lothario, Mrs. Alberti considers him worthy of the hand of his sister and by all means contributes to their rapprochement.
Once in the living room of Mrs. Alberti, Jean Sbogar speaks. A venerable old man once knew him. Originally from a noble family, in childhood this robber had a tender and noble soul, and only the circumstances of his life forced him to step on the path of crime. Having abandoned his father's name, he began to be called Jean Sbogar. Aotario also ardently defends the rebel robber. Antonia listens to him as if spellbound.
Lothario confesses to Antonia love. Anthony reciprocates. Shocked Lothario leaves the city, leaving Anthony a letter stating that he is not worthy of her love.
Antonia realizes that some terrible secret is hidden in Lothario's past. She finds a notebook dropped by Lothario, where he writes indignantly about the justice prevailing in the world.
Wanting to dispel her sister's sadness, Mrs. Alberti takes her home. On the way, they are attacked by the robbers of Jean Sbogar, they grab Antonia and bring to the castle of Duino. Ataman, a young man whose face is hidden by a mask, grants her freedom. Not wanting to leave alone, the girl is everywhere looking for her sister. Seeing in the chapel of the castle a coffin with the body of Mrs. Alberti, she goes crazy. Ataman, without taking off his mask, looks after Anthony.
But the robbers were captured and sentenced to death. Unhappy Anthony is placed in a monastery, where her mind gradually returns to her.
But Jean Sbogar was not found, and the authorities decide to show the captive robbers of Antonia - in the hope that she will recognize the chieftain, since she is the only one he spared. Among the prisoners, Anthony notices Lothario. "Lothario!" She screams. “I'm Jean Sbogar!” - answers the robber, and Anthony’s heart is breaking. Jean Sbogar goes to execution.
