一位物理学家用热力学定律来描述浪漫感情，但他的理论却被自己的爱情生活所证伪。
In Barcelona (Catalonia, northeast Spain), Manel is a neurotic scientist obsessed with the idea that the three laws of thermodynamics rule the daily life of all people, writing a thesis about it while he works as teacher assistant in the university. His happy life with his long-time girlfriend Raquel ends the day he casually crashes in the street at the same time as sexy, famous top model Elena; beautiful young lawyer Eva who has just opened her own law firm; and his friend Pablo, an Argentinian CEO of an advertising company and an unstoppable womanizer. After the incident, Manel breaks up with Raquel and starts dating Elena at the same time that Pablo dates Eva. Pablo and Eva's relationship is casual sex only; Manel and Elena live an idyllic love story. But Manel's neurosis and compulsive behavior eventually frustrate Elena, in his belief that everything is because of thermodynamics. Eva eventually leaves Manel and he tries to get her back; meanwhile, Pablo, after falling from a double-decker bus, tries to get Eva back after she breaks up with him after he insists that they have a threesome with another girl. Interspersed throughout the film is talk from real scientists who explain the laws of thermodynamics which rule the universe, from the Big Bang and the scientists who discovered it all through history. Pablo questions himself after he finds out that Eva's pregnant: can he be a husband, father, and family man? And Manel questions himself whether he can restore his previous life with Elena, or if the thermodynamics will make such reconciliation impossible.
