The Birth of an Assasin by Tony Bertot is a story a young boy called Theo. Theo grows up in a world of Italian mobster crime families. Losing his father to a mob bomb in his own shop, he and his mother flee to their homeland of Palermo, Italy.
The time frame is WWII so Italy is itchy with Nazi German posts. It is there in the homeland where Theo learns to shoot and he becomes very skilled at it. It is also here that his mother is brutally raped and murdered and Theo decides no one will ever hurt anyone he cares about again. He avenges his mother's death and then sets out to avenge his father's death in the US.
Theo and his boyhood friend, Nick, have a few adventures in catching up with the people who were responsible for Theo's father's death. In the end, justice is served, but at a great loss.
The Birth of An Assassin is the prequel to The Heart of an Assasin. Both books can be ordered here.