Aquí iba el himno

Two young men of privilege, Ricardo and Alain, take Ricardo's father's Audi into a rough part of Mexico City to buy drugs. Their purchase complete, they are pulled over by four men with badges who take them to a deserted park and demand money. A long afternoon leads well into night: the kidnappers' demands change, Alain is sent to find money, Ricardo is told that Alain is dead, and a police car appears and brings hope. Who are the kidnappers, and how will this play out?