Let no one accuse Audrey Tautou of excessive caution in her career choices. With last year’s amazing success as the title character in the hit comedy Amélie, Tautou conquered U.S. audiences and stood poised to be an international star of huge mainstream appeal: the lovable and non-threatening Frenchwoman, a crossover France Lite who could consistently break into the multiplexes.

Tautou’s new film, He Loves Me, He Loves Me Not…, with its cute title and Valentine’s Day release date, gives every impression of conforming to this plan: an upscale date movie. Until, that is, about 45 minutes into the story-when the plot does a breathtaking U-turn from soap opera into Hitchcockian suspense. This turns out to be not an easy-on-the-eyes date movie with subtitles, but a thrilling intellectual excursion into madness.

The first 45 minutes work well enough on their own terms. Tautou is likable, but a little unsettling, as Angélique, a young woman in a love affair with a married man. The man is Loïc, a handsome doctor (played solidly by Samuel Le Bihan), who causes Angélique a great deal of anguish by deciding he belongs with his wife after all. So far, so good; it’s the love-triangle movie we’ve seen any number of times, done a little bit better than most. Until, that is . . . The plot twist is intelligent and convincing, and a source of pure joy to the viewer; so it shouldn’t be ruined. Anyone who wants to avoid SPOILERS should skip the next paragraph completely.

Angélique’s problem, it turns out, is not that her lover has abandoned her, but that she is completely insane, and has imagined the love affair in its entirety. She is merely housesitting for Loïc’s neighbors, and has developed an obsession with him-an obsession that does not stop short of violent crimes. This second half of the movie is told from Loïc’s perspective, as he grapples with the mystery of who is sending him all these mysterious gifts and notes; his marriage itself is threatened when all the unusual events make his wife understandably suspicious.

This is the first feature-length movie of director Laetitia Colombani, but she manages some difficult emotional transitions with a firm hand and a veteran’s assurance. Also noteworthy is the adorable Sophie Guillemin as Angélique’s friend Héloïse; she was great in the 2000 suspense movie With a Friend Like Harry, and deserves more substantial roles.

I am not 100 percent certain, but I thought I saw out of the corner of my eye the nameplate “J. L. BORGES” on the door of one of Loïc’s physician colleagues. This affectionate wink at the viewer would be quite appropriate, because the film does indeed achieve a Borgesian combination of passionate love and intellectual labyrinth.

This is a very black comedy, with some good laughs in its dark Valentine’s Day heart.