Pablo, a Madrid banker in his 30s, has more chips on his shoulder than brain cells. He runs into rich, snobbish Sonsoles in a traffic jam but his attraction for her vanishes when he finds out she's put in a claim for injuries. Bored with life, Pablo decides to play mind games with Sonsoles. He follows her to a school where she picks up her 15-year-old sister, Maria. After Pablo makes anonymous dirty calls to Sonsoles, the latter asks a cop friend, Alfredo, for help. So Pablo decides to trail Maria. After meeting with Maria in a park and pretending to be a police officer, he's becomes obsessed by her.