An unusual string of murders - overweight women who were drowned and then dumped all over town, with a small chunk of flesh removed from their feet - brings the BAU to LA.
When the UnSub kidnaps another woman, the team attempts to hone in. They hold a conference in the hopes that someone came into contact with their UnSub and survived.
They find a woman, Bailey, who had been kicked out of the UnSub's taxi earlier for putting on perfume.
The driver is a scientist, and the parts of victims' feet were samples. He is obsessed with smell, and has been kidnapping women in order to chemically distill their scent.
Using the information they got from Bailey about the UnSub's taxi, they track him to his garage. They manage to save Anisa in the nick of time, but the UnSub escapes.
A long car chase ensues, ending in the UnSub's death.
We learn more about Prentiss' mysterious past as a special agent catching terrorists in Europe.