Back in the early 70s, a big-deal law partner (Mark Ruffalo) at a Cincinnati firm that specialized in defending chemical corporations was approached by a farmer (referred to him by the lawyer’s Kentuckian grandma) whose cattle were all dying strange, mutated deaths.

He reluctantly agreed to take a quick look, kicking off what would become a years-long crusade to hold DuPont responsible for knowingly polluting a small town’s water supply with toxic substances created in the manufacture of Teflon (awkwardly in a local plant that was the town’s biggest employer).

This is the deeply unsettling, true story (based on the New York Times Magazine article “The Lawyer Who Became DuPont’s Biggest Nightmare” by Nathaniel Rich) of Rob Bilott, a truly dogged man who stood up to great corporate bullying — delays, threats, inundating amounts of “discovery” — and risked everything to protect the public when the system failed to do so.

Though Anne Hathaway and Tim Robbins have what amount to extended cameos, this one belongs to Ruffalo (executive producer and an environmental activist in his own right). He’s spot-on as the modest, smart David who takes on a rich, arrogant and monumentally indifferent Goliath.

If there are criticisms to be made, they are, oddly, of a flattering nature. Crusading films exposing corporate malfeasance should be made, many of them, and watched by everyone. But they’re not all that hard to do, even ones as good as this. So the consensus is that, while wanting to make a muckraking movie is entirely understandable, a director with the unique gifts of Todd Haynes should now, please, go back to such enthralling and insightful efforts as Far From Heaven, I’m Not There, Velvet Goldmine and Carol. Just sayin’, (126 min)