Sara, a sensitive and beautiful young woman, whose only reason to live is her inability to die. Mario, a lover who wants his brief encounter with love to last forever. Jaime, a charming serial killer, equally capable of both seduction and destruction. One morning just like any other in Madrid, two perfect strangers, Sara and Jaime, are just two more people standing on an underground platform. A man falls onto the tracks as the train pulls up. For everyone there, it´s a tragic accident. But not for Sara. Horrified, she believes she saw Jaime push the victim onto the tracks. She decides to blackmail the killer. The hunter and her prey become involved in a perverse and increasingly intimate relationship, at a distance. Despite their use of all kinds of modern methods of communication such as mobile phones, internet and web cams, the two main characters feel the sheer loneliness of life in a city with four million dwellers. This feeling of loneliness, the way in which they use each other ...