It’s about the string of sex-related murders that took place outside Florence from the late 1960s to the mid-1980s. “Il Mostro,” which translates as “The Monster,” is the moniker given to the alleged serial killer who committed eight double murders, preying on couples parked in cars in secluded places around Florence. The still unsolved case marks one of the longest investigations into the most brutal serial killings in Italy’s history.