"Possessor" is a world-class body horror movie that has no idea when enough is enough, and no interest in finding out. Although much of the film is characterized by an eerie stillness and a distinctive sense of hovering dread, there are also episodes of ferocious, bloody violence, and there is one sex scene of a tumescent nature not usually found outside the overheated alleyways of porn. (This is in the unrated version of the film that's currently playing in theatres and drive-ins; an R-rated version is being readied for later on-demand viewing.)

The writer and director, Brandon Cronenberg, is the son of David Cronenberg, past master of icky ideas and disturbing imagery, and "Possessor" echoes some of the dank gloom of his 1983 film "Videodrome." But Brandon has creep-out skills of his own, and he's brought them to bear intensely in this madly complex puzzle-film.

Andrea Riseborough (Nicolas Cage's doomed girlfriend in "Mandy") is Tasya Vos, a woman with a husband, a son and a side job as a brain-burrowing corporate assassin. Her work requires the cranial implantation of a cyber worm that allows her to take over the body of a designated target. For example, her latest assignment, overseen by an agent-handler named Girder (Jennifer Jason Leigh), requires her to meld with the mind of Colin Tate (Christopher Abbot), boyfriend of Ava Parse (Tuppence Middleton), who is the daughter of obnoxious tech mogul John Parse (Sean Bean). Tasya's assassination bureau has been hired by Reid Parse (Christopher Jacot), John's disgruntled stepson, to murder John and Ava and set up Colin as the killer, clearing the way for Reid to inherit the family fortune. Tasya's part in this operation is to take over the body of Colin, have him kill John and Ava and then kill himself — right after she has signaled headquarters to pull her out from his mind and back to safety. "A clean tragedy," says Girder. "No unanswered questions."

The bending of gender and identity in this movie is incessant (and sometimes confusing), and it enables little jokes — like the scene in which Tasya, newly installed in Colin's body, peaks down into his/her pants to assess the unfamiliar appendage she's just acquired. Generally, though, laughs are scarce here. As Tasya's own mind starts breaking down, she finds herself involved in a shell game of slippery personalities, some of whom prove surprisingly difficult to defeat.

With its gouged-out eyeballs, fiercely pulped faces and whatnot (the fingers of a severed hand go on wriggling as if in farewell to its departing owner), "Possessor" could pass for a straight gore movie. The grisly stuff isn't entirely new, maybe, but the director holds on it at unnerving length. (One scene in which a character gets his face beaten in with a poker might leave you feeling as if you've been worked over with a fireplace implement yourself.)

What lifts the picture above its unstinting mayhem are the actors: Riseborough creates a harrowing portrait of a woman crumbling into existential confusion, and Leigh's character is amusingly blase about the gruesome particulars of her job. Also key are the intoxicating cinematography (by Karim Hussain) and production design (by Rupert Lazarus). Director Cronenberg has dispensed with digital effects and creates much of the film's alarming magic by old-school means — with gels and other lighting strategies. Some of the most hallucinatory scenes are bathed in an arterial haze, while others play out in shadow.

You might not expect a movie that begins with a shot of a woman driving a needle into her head to find many directions for development. But the horrific conclusion of "Possessor" sets a new standard for both cinematic savagery and slick sci-fi screenwriting. As Tasya's brain-jarring implants start to affect her marriage, she has to wonder: "Are you really married to the man, or are you married to the worm?"

Photo credit Neon.

Kurt Loder is the film critic for Reason Online. To find out more about Kurt Loder and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.