You can never be sure which Gus Van Sant you're getting when you are about to watch a film by this stylistically promiscuous director. Will it be the sympathetic chronicler of outsider teens ("My Own Private Idaho," "Paranoid Park"); the maker of mordantly funny black comedies ("Drugstore Cowboy," "To Die For"); the mainstream hit-maker ("Good Will Hunting," "Finding Forrester"); or the leading American exponent of slow cinema ("Elephant," "Last Days")?

Well, guess again. With "Promised Land," we get the mainstream-activist Van Sant of "Milk," this time working on a tale that looks at how fracking — the practice of extracting oil from shale deposits via high-pressure blasts of water mixed with sand and chemicals — is dividing small-town America. If I tell you it stars Matt Damon, you'll no doubt expect a bog-standard social-issue film, well-meaning but a bit dry, with more attention given to "the message" than the characters.

Van Sant, working off a story by Dave Eggers, provides a twist this time. Damon plays Steve Butler, a sleazeball corporate lackey who uses his small-town roots to come across all down-home as he convinces local landowners, mostly farmers, to sign away extraction rights. The kicker, of course, is that he has to play down the known risks of groundwater contamination, risks that have the potential to destroy farming communities.