Benedict Allen begins his quest in New York where he attempts to demystify the religion of voodoo.

Benedict Allen visits northern Haiti with a mambo, or medicine woman, for the festival of Ogun the Warrior, where he is unwittingly watched by a witch doctor with a notorious reputation.

This week Benedict Allen visits the Mentawai people on the rainforested island of Siberut in Indonesia. Under the tutelage of a young medicine man, or kerei, he tries to learn one of their sacred healing songs - knowing that if he gets the song wrong, the patient dies.

Benedict Allen is led into Indonesia's Siberut forest by Amam Dirikogo, a young kerei or medicine man, and comes across a rare species of singing gibbon. Concluding his training as a kerei, he attends a cleansing ceremony, and spends a night alone on one of the country's most sacred hills.

Benedict Allen's exploration of the shamanic world takes him to Central America, where he joins a group of Huichol Indians from Mexico's western Sierra Madre on their annual pilgrimage to the desert of Wirikuta in search of the peyote cactus. A powerful hallucinogen, the Huichol believe peyote enables them to communicate with the gods.

Continuing Benedict Allen's exploration of the dramatic world of Mexican witch doctors, medicine men, and shamans. In this second part of his travels in Mexico, Benedict Allen samples peyote, the cactus revered by the Huichol Indians. A small amount of the bitter-tasting flesh gives him a rare chance to see for himself the hidden realm of the gods.

Benedict Allen arrives in Siberia on the final leg of his journey into the world of witch doctors, medicine men, and shamans. This week and next he visits Tuva, where shamanism is experiencing a rise in popularity after 70 years of Soviet domination almost succeeded in wiping it out.

Benedict Allen concludes his exploration of the world's medicine men in the Siberian republic of Tuva. Allen seeks out an old shaman who gives a detailed description of the spirit world and speaks of energies he can feel as he heals.