In "Mrs. Soffel," director Gillian Armstrong is so enthralled with her feminist message that she never lets her story breathe. Based on actual events, it's not a movie so much as a historical object lesson hammered home, as if the Iron Maiden had come to the cinema.

The Biddles, Jack (Matthew Modine) and Ed (Mel Gibson), are Robin Hoods in the desolate steel-and-coal robber barony of turn-of-the-century Pittsburgh (photographed evocatively by Russell Boyd). They've pulled off "90 robberies in 90 days, and never hurt one citizen"; but, The System being what it is, they're convicted of a murder they didn't commit.

The derring-do duo is befriended by the tabloid press (which, as it is read aloud, provides the film with its bluntly obvious exposition) as well as women everywhere, who, motivated by either a sense of injustice or Mel Gibson's irresistible blue eyes, besiege the hoosegow with cries of "Free the Biddles" and gifts for the boys. But one woman in particular -- Mrs. Soffel (Diane Keaton), the warden's wife -- becomes their best friend of all.

Mrs. Soffel is a bedridden neurasthenic stricken with a disease that, while it puzzles her doctors and husband (Edward Herrmann), proves to be no more mysterious than a bad marriage. She has nightmares of suffocation, echoed in the cinematography, which is so darkly claustral you can almost smell the stale air of Victorian hypocrisy. And as she strolls through the prison, distributing Bibles to the inmates, Armstrong photographs her through the bars (she's "imprisoned" too -- get it?).

Mrs. Soffel thinks God will bring her salvation, but what she really wants (and, as a woman of that era, can't have) is sexual satisfaction. Bringing the Good Book to Ed, she's captivated by his swarthy good looks and azure gaze; after rattling on at each other about why God makes man suffer, they get down to business, holding hands and kissing through the prison bars. Mrs. Soffel smuggles two hacksaws in her Bible, and the three of them hightail it into the snowy countryside.

Mrs. Soffel has no illusions about why Ed has seduced her -- she's his ticket out of the hangman's noose, and his quaint love poetry doesn't fool her. In a nice montage of competing glances (Keaton and Gibson lock eyes while he picks up the Bible she's dropped), Armstrong makes it clear that the attraction is purely sexual. The lady is a tramp, and more power to her. But once that point is made, the movie has little to go on. Armstrong is a technically proficient director. But in shooting the sex scene, her camera dollies out of the bedroom like an abashed peeper before Gibson is halfway through his partner's petticoats. Sex proceeds with such impeccable reserve that when the movie champions sexual freedom it seems disingenuous.

Worse, the overall setup is one big cliche' in which the sympathies are stacked. Behind his pince-nez and waxed moustache, Herrmann's warden is starchy and unappealing; Gibson, on the other hand, plays Ed with a fine, engaging impersonation of Henry Fonda. Matthew Modine's ebullience (what an infectious cackle he has!) contrasts with the mournful mien of the symbols of authority, who appear in the movie as a sort of human wall of insensitivity. In attacking Victorianism, Armstrong has created a story with all the exaggerated earmarks of Victorian melodrama.

Keaton struggles mightily to make Mrs. Soffel more than a prop in an argument; but her strategy is Method acting, and in looking into herself, she finds anything but a Pittsburgh matron in 1901. Though she tones down her shtick, this most contemporary of actresses can't help clashing with the period setting.

Along with her "My Brilliant Career" (and after a brief detour into the charming "Starstruck"), Armstrong seems to have embarked on a sort of filmic PhD in women's studies, dredging up historical examples of femmes fatales who transcended times in which their career and sexual aspirations were denied. But these battles were fought, and won, years ago. Victorianism was bad for women -- who cares?