A small change in the drug market generates multiple side effects in neighborhoods that support drug trafficking. This ‘butterfly effect’ that is experienced harshly this autumn in the Raval, in Barcelona. A journalistic investigation by EL PERIÓDICOpublished in 6 installments from last Friday to this Monday, reveals the main keys to the new drug crisis in Ciutat Vella. The evolution of drug floors is behind the increase in images of drug addicts on the street and neighborhood complaints. There is no more drug but it is sold differently. The reopening of borders after the pandemic is also already noticeable, which oxygenates the global black market once again.