Benson and Stabler investigate what they assume to be the murder of a prostitute. Their assumptions change once they talk to the victim's middle class parents who assert definitively that their daughter was not a street walker. Further investigation uncovers that the woman may have been the victim of a serial killer. Ultimately they capture the serial murderer who turns out to be cop, but also finger the young woman's boyfriend who copycated the killer's m.o. to cover his crime.