When an experimental serum is given to an elderly alcoholic dubbed Patient 13, the old man begins to become physically younger. Before comprehensive testing can be done, however, the old man escapes the lab facility and disappears. Lucky O'Donnel finds Thirteen wandering in a local park and takes him in. Hypnotic regression reveals that Thirteen has a whole array of memories, some of them of ancient civilizations in Egypt, South America, and Europe. Meanwhile, a ruthless international corporation, the parent of the local inventors of the serum, sends agents to retrieve the errant Patient Thirteen with the potential prize of a formula that could induce physical youth in its users. The Memphis Corporation isn't too concerned if Thirteen is returned to them alive or dead.