Diego and Clara have just met and, nevertheless, decide to move in together. Their house is in the middle of a big city and is divided into two floors. An old man, José, lives upstairs, and the one downstairs, the one that is rented, has the rare peculiarity of having its walls covered with written messages. Diego gradually becomes obsessed with the subject and discovers that the graffiti are related to each other and that they were written by the man and the woman who had previously occupied the house.