In a future world devastated by disease, a convict is sent back in time to gather information about the man-made virus that wiped out most of the human population on the planet.
Having made a deal with the Devil himself for immortality many millennia ago, the now decrepit mystic Doctor Parnassus fights for the freedom of his only daughter's soul.
A former radio DJ, suicidally despondent because of a terrible mistake he made, finds redemption in helping a deranged homeless man who was an unwitting victim of that mistake.