"Asylum," Patrick McGrath's fine 1997 novel, tried to pussyfoot around its soap-opera plot in proper highbrow fashion, but the movie that director David Mackenzie has made from the book has no such reservations. This tale of a psychiatrist's wife and her doomed passion for an inmate is melodrama in the old-fashioned, hyperbolically elegant tradition, one that reaches back to the great black-and-white Warner Bros. tempests of the 1940s. If it falls short of that tradition, it's still a classy unintentional hoot.
Natasha Richardson is coolly gorgeous as Stella Raphael, who when the film opens is arriving with her husband, Max (Hugh Bonneville), and young son, Charlie (Augustus Jeremiah Lewis), at a dungeonlike asylum for the criminally insane in rural Yorkshire. The year is 1959, the locals are stuffy, and Max, the asylum's new deputy superintendent, is a humorless dud. No wonder Stella seems ready to explode out of her tightly wrapped low-cut dresses at any moment.
Then she catches a glimpse of Edgar Stark (Marton Csokas), a smoldering inmate who has unwisely been allowed to tend her garden, and on goes the crimson lipstick. It's only a matter of time before it gets smeared off, and the couple's assignations in a crumbling greenhouse carry a tawdry erotic charge. Like Stella, the metaphor's there for the taking: There are many stones being thrown in this glass house, and she and Edgar do most of the tossing.
Watching this literal amour fou from a discreet distance is Dr. Peter Cleave (Ian McKellen), the asylum psychiatrist who has long carried a peculiar sort of academic crush on his pet patient and who fears that Stella may be a rival for emotions he's not ready to confront. He whispers Edgar's case history into her shell-like ear: a sculptor given to fits of jealousy, a wife who brought out his inner demons, a dark and stormy -- but I've said too much already.
At a certain point, ''Asylum" becomes less about this affair and more about Stella's step-by-step degradation; she begins as the film's prime mover and ends as its exquisitely ravaged victim (admittedly, after victimizing everyone else within reach). Lovers of old movies will understand when I say that she starts the movie as Joan Crawford and ends it as Joan Fontaine, and the film itself seems to have the Turner Classic Movies playbook in its back pocket. McKellen makes a reasonable stand-in for Claude Rains, and who but Farley Granger for the role of the impossibly handsome, undeniably bonkers Edgar? There's even a nod to Hitchcock's ''Vertigo" toward the end.
What ''Asylum" never convinces us of is why any of this should matter. There are some extremely smart people behind the camera, including co-screenwriter/playwright Patrick Marber (''Closer") and director Mackenzie, who made last year's ''Young Adam," the atmospheric, sexually explicit, and curiously remote Ewan McGregor film. ''Asylum" is at a similar remove, with the added weight of melodramatic contrivance holding it down, and after a while the film turns merely preposterous.
Nor does Richardson, for all her skill and glamour, ever let us in. This is less of a problem in the early scenes, but when Stella makes a few serious -- and I mean serious -- errors in judgment, an audience wants more than moody stares into the middle distance. The morbid interiority of McGrath's novel has been turned into distressed gloss, and while it's awfully nice to look at, it never once comes close to the dangerous emotions of the real thing.
Ty Burr can be reached at tburr@globe.com.