For those of us who believe in it, there is destiny. There's one person you're destined to spend your life with or at the least, one person you're destined to spend your early 20s with a couple years you're destined to enjoy spending single (the pre-ordained "finding yourself" years), and one person you're destined to buy a house with and later discover is cheating on you. Destiny is what you make it--at least according to Sex and Lucia.
After reading local writer Lorenzo Alvarez's novel, Lucia shows up at a bar where he drinks, pledges her love to him, and says that they should move in together immediately. He accepts, and so their intensely sexual and loving relationship begins. As the two become closer, Lorenzo discovers he has a daughter with an anonymous woman he met while vacationing on the island where he was born. He keeps this from Lucia, and fantasizes about both his daughter's life and the life of her young, confused babysitter, and spends more and more of his time writing about them in his novel, and less time with Lucia.
As their relationship hits an absolute breaking point, tragedy strikes, and destiny turns another corner. Lucia flees Madrid, visits the island where Lorenzo was born, and slowly discovers she is among people who are integral to his secret life.
The title of the film is misleading, because it is more of an adult fairy tale--exploring the mystical and logistical aspects of Lucia and Lorenzo's relationship and lives-- than it is an exploration of Lucia's relationship with sex (although there are some great sex scenes that include the rarely-seen male frontal nudity). The scenery is beautiful, the acting is great, and Lucia (played by Paz Vega) is reason enough to see the film, considering she's one of the most beautiful women ever. Peripheral characters are compelling and add depth to the story, and in the end, the collision of the serendipitous relationships is charming, rather than contrived. Ultimately, the film is motivating--it posits that destiny exists, but you have to go out and find it.