L'estate di Davide

At 19, David has his diploma (the first in his family), a job at a car wash, and little else. His family is broke and argues constantly. So, unannounced, David leaves Turin for his uncle's farm. The gruff uncle sets David to work, and softens as the youth proves himself. When David is injured, Patrizia, who works at a nearby factory, drives him to hospital. There he meets the outgoing Alem, a Bosnian who's always on the hustle. Once healed, he continues these relationships, but all three (with his uncle, with Patrizia, and with Alem) change irrevocably when drugs enter the picture. Who is Patrizia's friend with the black Mercedes? What will David do when he finds out?