“I'm Thinking of Ending Things,” a psychological thriller by the young Canadian writer Iain Reid, begins innocently enough. A young man named Jake and a young woman who remains nameless are in a car in the middle of nowhere, heading toward his parents' farmhouse for her first visit. They are boyfriend and girlfriend. They haven't been in the relationship for very long.

Judging by the way the unnamed girlfriend talks (she's the narrator), they may by splitsville by the time they reach their destination. “I'm pretty sure I'm going to end it,” she says. But being that she's just described the “rare and intense attachment” she has with Jake and goes on to say what a good spooner he is in bed, we're not quite sure what she's thinking.

We can understand her ambivalence. Jake, who does all the driving, is a bit of a drip. He seems to be talking to himself more than her. His idea of conversation is serving up what he considers deep insights: “You're never just sleeping. ... Not even when you're asleep.” ”

In saying she's going to “end it,” could the girlfriend mean she's contemplating suicide? Her life, she says, has been “lacking a dimension. Something seems to be missing.” She keeps dodging incessant cellphone calls from a stranger who leaves unsettling messages: “I'm scared. I feel a little crazy. ... Now is the time for the answer. Just one question. One question to answer.”

A lot of bizarre sights and scenes await us in “I'm Thinking of Ending Things:” photos of body parts in Jake's old bedroom; a Dairy Queen from hell where a counter worker has strange bumps on her arm; an abandoned high school where, in the middle of the night, Jake insists on finding a proper trash can in which to deposit their used frozen dairy cups. Plenty of things go bump. There will, we fear, be blood.

However creepy the circumstances, though, it's the disembodiment of the characters that grabs us the most. What happens plotwise in “I'm Thinking of Ending Things” — even in its tingliest moments — is of secondary interest.

In fiction, as in music, many artists master the strategy of tension and release, by which a story builds and builds in intensity, leading to an outpouring of emotion or energy that frees us to move back from the edge of our seat. Reid, a Canadian whose writing seems influenced by the great Toronto-based filmmaker David Cronenberg, is a master of tension — and more tension. Never does he release us from his unsettling grip.

What some readers may want to be warned about is the deep unease they will experience as Reid unmercifully zeroes in on things we usually don't like discussing, like inescapable sadness. “What if intelligence leads to more loneliness rather than to fulfillment?” posits the girlfriend. What if human connection is a myth? And the cruncher, as stated by the girlfriend: “What if suffering doesn't end with death?”

That's a lot of philosophic weight for a slim, 200-page volume to bear. (Jung gets name-checked, as does Thomas Bernhard.) But with his relentless attack and edgy, pared-down, sneaky prose (note how the girlfriend says “a hand touches my leg,” not “his hand”), Reid pulls it off. We could probably do without the brief italicized sections that offer teasing exchanges between unidentified parties (“It must have been terrible to stumble across”). But in introducing a “normal” outside consciousness, these inserts have a way of heightening the prevailing abnormality.

In addition to Cronenberg, the ghost of Stephen King hovers over these pages: Reid pays homage to “The Shining” with four pages consisting of nothing but the line “What are you waiting for?” The chilly postmodernism of J.G. Ballard and deadpan sci-fi narratives of Jonathan Carroll also figure in the writing. But for all that, this is the boldest and most original literary thriller to appear in some time.

With its deep enigmas, “I'm Thinking of Ending Things” is the kind of book that encourages at least one rereading — and a slow and attentive reading at that. The characters themselves may not have more secrets to reveal, but the dense psychological space they're traveling through remains as full of dark surprises as your friendly neighborhood black hole.

Lloyd Sachs is a freelancer.