His heart was a prey to hatred and revenge.

He undertook to communicate with Giacomo Cenci, without whose concurrence the women would not act, as he was the head of the family, when his father was left out of account.
Giacomo entered readily into the conspiracy.

It will be remembered what he had formerly suffered from his father; since that time he had married, and the close-fisted old man had left him, with his wife and children, to languish in poverty.

Guerra's house was selected to meet in and concert matters.
Giacomo hired a sbirro named Marzio, and Guerra a second named Olympio.
Both these men had private reasons for committing the crime--one being actuated by love, the other by hatred.

Marzio, who was in the service of Giacomo, had often seen Beatrice, and loved her, but with that silent and hopeless love which devours the soul.