S4, E3: The team's newest member, FBI rookie Elena Delgado, formerly of the NYPD, encounters a learning curve as she attempts to help search for missing 20-year-old Dina Kingston. The team soon discovers that Dina is a prostitute whose ransacked apartment contains the charred remains of her black book of clients. Further investigation uncovers that Dina, who had recently attempted to commit suicide, was suddenly desperate for a large sum of money, which caused her to be much less discerning about her clients as shefeverishly solicited more business. The street-savvy Elena, who had excelled in the NYPD's vice unit, initially believes this particular case is better suited for the homicide department. However, the team's subsequent leads and methods make Elena realize that, whether Dina's found dead or alive, Elena has definitely got a great deal to learn about the Missing Persons Squad.