The mother-in-law in question is Martha, played by Jessica Lange. She has been single-handedly running the family horse farm, Kilronan. Her son, Jackson (Johnathon Schaech) and his girlfriend, Helen (Gwyneth Paltrow), live in New York, and have no intention to move back down south to the rural Kilronan. But those intentions are about to change.
You see, Martha lives by manipulation. She has used it in years past to breed many championship horses. Now, she believes she can use it to breed herself a grandson. Though at first, Helen finds Martha charming, soon she is caught in the domineering Martha's web of deception.
It's hard to understand why nobody ever wises up to Martha' schemes. As written, most of the characters in the film must be very slow witted. But then, the film even treats the audience like idiots. It tries to get away with things (like leaving a critical piece of evidence in a rather unlikely place) without even batting an eye. Then again an audience which accepts characters as shallow as these isn't one that's likely to question details.
Jessica Lange's Martha is the only semi-developed character in the film, and she applies her talents to redeem it as much as she can. A character that could have been simply awful is merely groan-worthy. Gwyneth Paltrow doesn't have much to build upon, as Helen's only character trait seems to be "daughter-in-law". Still, she fares better than Johnathon Schaech, whose character is so nonexistent, he's inexplicably missing for much of the film.
Still, there have been much worse "____ from Hell" films. Even with its paper-thin characters and ludicrous setups, Hush manages to create a few thrills in a color-by-numbers fashion. You know what's coming, but occasionally the film will deliver a shock or two. The old formulas are around for a reason, but that doesn't mean they taste fresh.
[PG-13 - some violence, sensuality and brief strong language] (TriStar)