In the modern American memory of the 1960s, the Black Panther Party is presented in three images. First, and perhaps most pervasive, is that of a violent organization of angry African-American men and women — the people who marched on the California State Capitol Building in 1967 and wielded weapons during encounters with police. This perception of African Americans, armed and dangerous — a callback, in some ways, to the fear of slave uprisings and later, black political rule in the South — sparked demands for law and order across the nation.

The second image of the Black Panthers has been cultivated by activists and modern historians alike: an organization dedicated to local community activism, building political power, and delivering social services to those who needed it most. Seen in books such as Alondra Nelson’s Body and Soul: The Black Panther Party and the Fight Against Medical Discrimination, this version of the Panthers renders them armed not just with rifles and bullets, but with medicine and food.

A new documentary titled Black Panthers: Vanguard of the Revolution excels at discussing these first two images. It’s less adept at covering the third: an organization built on socialist principles and ideology.