The BAU heads to St. Augustine, Florida, where a young woman and an elderly man are found dead in a swamp area outside of the city, seemingly unrelated. The woman had her blood drained, and placed into the man's body. Based on the triangular cut mark in the man's thigh, what was known to be his ill health (specifically Parkinson's), and the young woman's healthy lifestyle, the team surmises that the unsub is using his victims for medical experimentation to find a cure for some disease. Animal DNA found in the male victim also shows that the unsub has some fantastical notions of what that cure could be. Another young woman, Andrea Gambrell, who was a colleague of the first female victim, goes missing, she who is deemed to be the next healthy subject for the unsub in his experimentation. They have to see if they can find another missing person as the "unhealthy" subject with some sort of neurological disorder to close in on the unsub. The nature of the animal DNA and the St. Augustine locale may provide more clues as to the unsub's end goal. Meanwhile, Garcia remains at BAU HQ, going a bit stir crazy.