Most horror movies, hoping to elicit a simple visceral response, aim squarely for the gut. Blood? Gore? Ewwww!

Splice, an unsettling, intelligent, and way-out-there experiment in bio-terror from Canadian director Vincenzo Natali, targets the chromosomes. Splicing human with creature DNA? Whoa!

Not since David Cronenberg's sexual-parasite tale The Fly (1986) have I physically experienced horror on the molecular level.

Frankenstein for the genetic-engineering generation, Splice itself splices together the mad-scientist story with a satire of modern marriage and parenting. While the results are mad, brazenly unethical, and occasionally funny, the implications are deeply upsetting.

The film focuses on married geneticists Clive and Elsa (Adrien Brody and Sarah Polley). Movie geeks will recognize that these hipsters (who dress like club bunnies rather than lab rats) are named after Colin Clive and Elsa Lanchester, the mad scientist and his creation in The Bride of Frankenstein.

Clive and Elsa are protein breeders. By splicing DNA from disparate animals, they look to synthesize a protein that will save lives - and their pharmaceutical company's bottom line. Married to their research, they are thisclose to achieving their goal.

But when the mating dance between their lab-created organisms ends in disaster, the couple regroup. Clive kinda wants to make real babies of their own, but Elsa - due to childhood horrors the movie alludes to but does not detail - is maternally disinclined.

She believes that the only way to create the protein, that killer app her company so desperately wants, is to introduce human DNA (her own) into the test-tube recipe. It goes against protocol, not to mention Clive's express wishes, but Elsa does it anyway. Quicker than she can say "Rosemary's baby," there's an embryo developing in the lab tank.

Terminate or gestate?

The pro-choice/pro-life debate is one of many hot buttons pushed by Natali's film. Can a baby save a marriage? Can parenting an infant heal the emotional wounds of childhood? How do we emotionally bond with creatures that are not fully human? Natali's horror movie stealthily morphs into a relationship black comedy before darting off again into other, unexpected, terrain.

Given the far-fetched and occasionally risible plot, Polley and Brody resourcefully ground their performances in relationship reality, which focuses the viewer on the emotional and ethical stakes rather than on the fantastic scientific breakthroughs.

Elsa's offspring, named Dren (read it backward), is gracefully and chillingly played by Delphine Chanéac, who suggests a CGI-augmented combination of Margot Fonteyn, Gollum, and a T-rex. It is a tribute to Natali's stylish direction and the film's heavy-breathing sound design that Dren seems entirely plausible even when the movie does not. Mess with Mother Nature, the film tells us, and her unnatural spawn may bite back.

Biologists and bioethicists might shudder at the film's contempt for lab protocols. But when it comes to eliciting shudders, Splice delivers.EndText