Human sexuality is a great mystery, someone declares early in this film. Maybe that’s director/co-writer Claude Chabrol’s best shot at explaining the arbitrarily debauched relationship between young television ingénue Gabrielle Deneige (Ludivine Sagnier) and the older, married author (Francoise Berléand) who seduces her with the single-minded aplomb of a gray-bearded egret swooping in to pluck a plump fish out of the sea. Meanwhile, she’s also being courted by the cute but unstable young heir to an unimaginable family fortune (Benoît Magimel). Chabrol is sometimes known as “the French Hitchcock,” and A Girl Cut in Two is a loose re-telling of the events surrounding the 1906 murder of New York architect Stanford White transposed to contemporary France. The title refers to Gabrielle’s two suitors, but also to the damage she suffers as a result of the dangerously naïve choices she makes. The performances are all superb, however, especially the 28-year-old Sagnier, who is quickly earning a reputation as one of the best French actresses of her generation, and Magimel, who has the tricky task of playing a charming but credible psychopath. Once the film shifts into high gear, it’s compelling, absorbing viewing — but it takes a very long time to get there. B-