I don't know if this one has been mentioned yet, but I just saw "The Sicilian Girl", and was really moved. It is based on the true story of Rita Atria who at 17 yrs. old takes on the Mafia in Sicily.
As a little girl growing up in a Mafioso family and neighborhood, she witnesses her father and brother get killed by rival crime families. Vowing to get revenge, she realizes she won't be able take them down with a gun, but rather her very detailed diary. She kept notes on the Mafia's dealings for years and brought the evidence to a prosecutor when she reached 17. She then becomes a "marked" girl when she dares to break the cosa nostra's long-standing "code of silence" rule.