In 1965, Indonesia went through a harrowing bloodbath in which the army encouraged civilians to murder anyone deemed an opponent of a coup that brought an officer named Suharto to power.
Indiscriminately labeled Communists, victims were ruthlessly slaughtered and hacked apart. More than a million died within a single year.
If this insane carnage sounds familiar to moviegoers, it's because of director Joshua Oppenheimer's Oscar-nominated documentary, The Act of Killing. In that gripping and bizarre 2012 film, Oppenheimer talked to perpetrators of the violence and had them re-enact the killings, which many spoke about with robust pride.
The movie was as difficult to watch as it was haunting, so it's hardly surprising that Oppenheimer couldn't let this subject go. Once you've seen into the heart of darkness, it's not easy to pretend that you haven't.
Oppenheimer's new film -- The Look of Silence -- adds to our knowledge of what happened in Indonesia, and gives us another glimpse into the minds of killers who remain unrepentant and even boastful about what they did.
But this time, we also get a feel for the torment of relatives who lost loved ones to the mob.
Oppenheimer builds his documentary around Adi, an optometrist whose brother Ramli was killed at Indonesia's Snake River, site of the murder of more than 10,500 people. Ramli died a year before Adi was born.
Adi visits the men who participated in the killing of his brother to fit them with glasses. Their vision may be improved, but few are able to see the harm in what they've done.
We also meet Adi's aging mother and addled father and are told that both may be more than 100 years old. Adi's father is lost in the fog of dementia; his mother remembers -- all too well.
A persistent interrogator, Aid conducts probing interviews with men who find ways to justify their ruthlessness and sometimes even talk about it with smiles on their faces. At times, they look like old men fondly recalling athletic exploits from high school days.
More than one of them reveals that in order to keep from going crazy, he drank the blood of a victim. That's not a metaphor. It's a literal statement about the ways in which some of these men swallowed their crimes.
We also meet the children of perpetrators. They're either embarrassed or defensive about what their fathers did. One expresses a sincere hope for reconciliation.
Listening to stories about mass killings -- recounted with exacting and graphic detail -- makes for difficult but necessary viewing: Each of these stories reveals how people attempt to justify even the most perverse behavior.
Time and again, Adi is told to leave the past in the past, but this past becomes an alarming part of our present, a warning about the crimes committed by men who are convinced that they're right.
Movies such as The Look of Silence ask us to look horror in the face in hopes that we won't allow it to be detoxified by time. It demands that we reconsider what we believe about the world in which we live. You won't soon forget it.