Long and slow, but interesting and well-acted (as you would expect from a cast headed by Meryl Streep, Kurt Russell and Cher), this revolves around the real-life Karen Silkwood, the plutonium worker who set out to expose contamination risks and other irregularities at her plant.
Streep's performance is something else; see it for that if nothing else.
And modern-day star-spotters will have a field day catching early appearances by Fred Ward, Ron Silver, Will Patton, Tess Harper and others.