Starting near the end and ending somewhere in the middle, Julio Medem’s “Sex and Lucia,” (“Lucia y el Sexo”) strings its audience along a sometimes confusing, seemingly disjointed ride that manages to come together in the end. Or is it the middle? Confused? I think that’s the point.

“At the end of the story there is a hole which takes you back to the middle,” explains Elena (Najwa Mimri), the former lover of a mysterious writer, Lorenzo (Tristan Ulloa), “From there you can take on a new course.” She’s referring to Lorenzo’s novel, written as the movie progresses. Lorenzo is a complicated man whose past inevitably brings about a great tragedy — which, for the sake of suspense, I will leave unnamed.

But Elena’s comments on the novel are just as applicable to the film as a whole. Lorenzo’s novel is based on the events of the film, and he writes his novel as those events take place on screen. For instance, after Lorenzo discovers Elena gave birth in secret to his only child, he writes a similar event into his plot.

With its innumerable twists and complexities, a full explanation of the film’s plot is nearly impossible and would necessarily ignore a number of possible interpretations.

Consider a brief summary: The audience first meets Lucia (Pax Vega), a waitress who gets a telephone call leading her to believe her lover, Lorenzo, has been killed. She escapes her anguish by running to an island of which he often spoke. There she meets Carlos (Daniel Freire), a scuba diver who leads her to a guest house occupied by Elena. These characters are connected by a conundrum of triangles that, when clarified by the Big Picture, is ingenious.

Getting to the Big Picture, however, is sometimes tedious. The characters’ relationships are complicated, and Medem further confuses them with his story-telling, switching between the present and the past and never resolving the future. Watching the movie indeed becomes a chore when the viewer attempts to focus solely on the whole.

But that’s exactly the point. Medem’s 1998 film, “Lovers of the Arctic Circle,” also began at both ends and met at the middle. Toying with the audience’s mind is his style. Medem confuses the audience to distract them from the inevitable outcome, instead focusing on the plot’s many parts. And each part plays out quite nicely.

The focal points of Medem’s picture are not the beginning, middle, and end, but rather the intricate human relations (hence the sex). Lucia asks Lorenzo, “Would you rather have wild sex with stranger, or sex with someone about whom you’re wild?”

How appropriate considering Lorenzo is currently in a relationship — or at least having sex — with Lucia, whom he’s wild about. But he is also forever a part of the life of a complete stranger, Elena, a one-night stand who bears his child. While there is a definite beginning to human relationships, Medem conveys that middles and ends are less surely defined.

The movie tells an interesting story in an interesting manner. Its greatest strength perhaps is the way in which individual relationships play out and interconnect. By disjointing the whole of the story, Medem forces the audience to pay closer attention to the parts rather than anticipate the logical whole. And in that respect, “Sex and Lucia” succeeds.