Near the beginning of Angels and Insects, our romantic protagonist courts the object of his very sexual affections in odd fashion. That scene, which involves a veritable swarm of butterflies and moths crawling across the woman’s clothing and skin, is a good indicator of the film’s ambitions. Putting a Victorian estate under the microscope, Angels and Insects postulates that this family unit, with sons, daughters and servants all tending slavishly to the needs of a bloated matriarch, is something less sophisticated and more distasteful than your average backyard ant farm.

William Adamson (Mark Rylance) is an outsider among the blueblooded Alabasters, the family whose patriarch, Sir Harald (Jeremy Kemp), rescued the young naturalist from a disastrous shipwreck. He is allowed to live with the Alabasters as Harald’s assistant, and swiftly falls under the spell of the oldest daughter, Eugenia (Patsy Kensit). This courtship among the insects is the film’s most direct metaphor, and its most satisfying conceit. As William confesses his love to Eugenia, he looses upon her what first seem to be the world’s loveliest butterflies. But soon, Eugenia is beset by the unsightly male counterparts to the beautiful females, which crawl across her body, drawn by female pheromones.

The trauma of that experience isn’t enough to derail the romance, which unfolds to the chagrin of Eugenia’s brother, Edgar (Douglas Henshall), who considers William an unfit suitor. Edgar’s sneering insults grow more and more provocative, but William resists his verbal exhortations to physical battle and marries Eugenia. His assimilation into the family is thus made literal, and Harald seems rather fond of the young man — but Edgar won’t let up, spouting continually about how little William knows of the world, and the significance of his improper breeding.

This socio-scientific Darwinism is as much a key to Angels and Insects as are the butterfly and ant-farm metaphors (when Eugenia proves herself to be less than an ideal lover, William bides his time with a detailed study of an ant colony on the estate). For the first hour or so, I was sitting on the edge of my seat, gamely tracking all of the asides, double entendres, and allegorical declamations. Philip Haas’s screenplay tries to cram all the thematic concerns of its source material (the novella Morpho Eugenia, by retro-Victorian scribe A.S. Byatt) into the two-hour space of a feature film, but it’s a little much.

Those concerns spill over from the story and dialogue into the film’s visual grammar, as well. While the overall production design is sumptuous and striking, the movie’s infatuation with its own color sceme grows tiring. For instance, when Kensit turns up in one of her show-stopping gowns, an unlikely peacock blue fringed in blood red, the effect is an imperfect distillation of the Peter Greenaway Effect — decidely garish in appearance, but relatively graceless in execution. More effective for my money is the less specific sense of dread that infuses the proceedings, especially in the scenes leading up to the marriage of the unlikely lovers.

So maybe it’s because the film wore me out in its first section that I found the second half fairly tedious. It’s mostly a waiting game. We know that Kristin Scott Thomas (she plays Matty Crampton, the family tutor) gets billing above Kensit, so her role will soon become prominent. The ad campaign has assured us that there’s a “startling” revelation in the final reels, but the punch is telegraphed across most of the movie. And, of course, we know that something’s got to give — and it does.

That having been said, the movie does have its pleasures. The performances are decidedly less mannered than we’ve come to expect from costume drama, and Rylance and Henshall make deliciously credible intellectual adversaries. I’ll even go out on a limb for Kensit, whose vaguely unsettling concupiscent charms have never before been put to such perfect use. The cinematography is lush and surprising, and the atmosphere is boldly creepy.

The opening credits sequence, which flash back to Adamson and a troupe of Amazonian dancers frolicking in the firelight, is more honestly sexual than anything that follows, and we get the sense that he was never happier than he was among the natives (as if to underscore the point, the titular letters spelling out Angels cross the screen in front of the dancers). This sequence, beautifully edited by the director’s wife, Belinda Haas, helps us understand the libidinous freedom that Adamson craves, even as he takes a luscious wife in an ostensible paradise. While the inhabitants of a less seething Victorian tableaux might negotiate apparently charmed paths to a satisfying but unlikely happy ending, we are made to grow more and more certain that the only resolution to the Victorian dilemma postulated by Angels and Insects is escape.