The whole film takes place in the mid-90s and is based on the true story of journalist Gary Webb (Jeremy Renner), who is presented with information that the CIA might have at least tolerated the massive influx of drugs into the US in the 1980s as a way to secretly fun the Contra rebels, who opposed the socialist Sandinista in Nicaragua. After publishing the story, Webb, who works for a smaller newspaper, finds himself under attack from established newspapers who pick his story apart and also target his personal life.
Even if you don't really care about the story itself, I think Renner delivered a strong performance and the supporting cast was on point as well and it all made for an enjoyable film. I give it a 7 or 7.5 out of 10.
Considering that the movie only made $2.5M at the box office ($5M budget), I imagine a lot of people haven't heard of it.
Trailer (haven't watched it myself)
Reading up on it after watching the film, the story presented in the movie isn't a 100% accurate and for example leaves out problems with Webb's story, but it definitely sparked my interest regarding the whole scandal. The movie is based on two books, "Kill the Messenger" by Nick Schou and "Dark Alliance" by Gary Webb, so there's definitely in-depth material to delve deeper into this topic. Also, the drug inflow (not just due to Contras) led to the crack epidemic in the 1980s, which is touched on in the movie and is a interesting topic itself.