“All families have at least one secret. Mine was no different.” But boy is this secret the kind that not every family has. Chilean filmmaker Lissette Orozco always had a favorite aunt, Adriana (aka Channy). She seemed the kind of affable family member who often told her how similar they were. That made her arrest in 2007 all the more surprising. She’s accused of having been a part of dictator Pinochet’s notorious secret police, Dirección de Inteligencia Nacional (DINA), which committed heinous acts during his reign. Orozco, wanting to tell the full story—and hoping to either exonerate her aunt or fully understand why she keeps denying the accusations—picks up her camera to work on what became El pacto de Adriana (Adriana’s Pact).

Mixing home movies and old family photos with teary Skype interviews with Channy as well as reporting on the DINA investigations, this documentary unearths uneasy family truths while offering a powerful history lesson on the atrocities committed in Pinochet’s name. Years in the making, this personal story is told in near voyeuristic detail—if the recently released trailer is any indication Orozco clearly doesn’t shy away from showing the anger and frustration both she and her aunt feel at having to cope with these shocking revelations. Check out the gripping trailer in full below, which reminds us that the personal is very much always political.