The Serpent and the Rainbow (1988)

Dennis Allan is a scientist who visits Haiti on the strength of a rumour of a drug which renders the recipient totally paralyzed but conscious. The drug's effects often fool doctors, who declare the victims dead. Could this be the origin of the "zombie" legend? Alan embarks on a surprising and often surreal investigation of the turbulent social chaos that is Haiti during the revolution which ousted hated dictator "Baby Doc" Duvalier. Often a pawn in a greater game, Alan must decide what is science, what is superstition, and what is the unknown in a anarchistic society where police corruption and witch-doctory are commonplace.