The BAU travels to Miami, Florida to investigate the beating and suffocation death of a young prostitute. Why the team is involved is because that murder follows similar type murders of puppies in the area, meaning that the unsub is evolving in his killings to humans and will most likely strike again. After the team's arrival, other similar murders occur, although each subsequent murder of prostitutes evolves in minor ways. Because of the locations of the bodies, the team believes they are dealing with a young person unsub, and because of the evolution of each subsequent murder, they also believe the unsub has an accomplice, an older person who acts as the mentor. What they also believe is that the young unsub will eventually feel like he can strike out on his own which means that there may be a stand off between the two, which in and of itself will not stop the killings. They have to figure out the true relationship between the two unsubs before any more dead bodies are found.