Dennis Alan, an ethnobotanist/anthropologist from Harvard University, narrowly escapes the Amazon Jungle at the beginning and returns to Boston. Word of his exploits gets around and he is approached by a large pharmaceutical corporation looking to investigate a drug that is part of the Voodoo religion in Haiti that they want to acquire in order to mass produce. They send him to Haiti to find out about the drug, but he winds up learning more about zombification instead. In essence, the drug is an alternate and less dangerous method of anesthesia.
When Alan arrives in Haiti the country is in the middle of a revolution of sorts. The government is taking anyone prisoner who they think is against the current political powers. He eventually meets another doctor who helps him research and investigate the so-called zombies. What he finds is the evil that lurks behind the Voodoo religion and the destruction it can cause to the human mind.