Cosme, a 15-year-old boy, sets his sights and his libido on his new neighbor, Merche. After giving her a lift on his moped, and getting a glimpse of her underwear, he begins to look for excuses to wander next door. He manufactures illnesses to stay home from school and uses his free time to ogle her while she sunbathes outside. His efforts to sustain a relationship that leads to the bedroom are hampered by his amusing family, sabotaged by the maid, and jealously noted by his high school girlfriend.

Cosme, un chico de quince años, vive con sus padres y su hermana en un chalet adosado. La monotonía de su vida cambia cuando se enamora de su vecina Merche, una hermosa mujer que tiene casi veinte años más que él.