IQUITOS, PERU -- Kevin Simmons, a 28-year-old Chicago native, said he "was stuck" -- depressed, locked away in his home and taking more than a year to even open his e-mail.

The road to recovery, he said, came deep in the Peruvian jungle, in the form of a sludgelike concoction the Indians call "the sacred vine of the soul."

The potion is ayahuasca, and increasingly, it is becoming an elixir for foreigners grappling with everything from depression to childhood trauma. Coming from the United States and as far away as Australia, they arrive in a jungle city of faded glory to participate in ayahuasca rituals offered by a range of healing centers.

Ayahuasca may taste like ground-up earth, but many leave here praising the brew in reverential terms for having purged them of demons and shown them a clarity about life that they never thought possible.

"It's provided a sense of okay-ness, this maternal reassurance that everything is all right," said Simmons, who now does environmental work in Panama. "It made me feel like trying again, reminding me of this beautiful internal world that we have."

This city, on the murky, chocolate-colored Amazon in northeastern Peru, has always lured outsiders seeking adventure, riches or redemption. Its heyday a century ago brought rubber barons, none more colorful than Carlos Fitzcarrald, inspiration for Werner Herzog's film about an obsessed would-be rubber magnate who hauls a steamship overland to reach a rich strand of rubber trees.

The end of the rubber boom brought decay to Iquitos, leaving once-opulent mansions in disrepair. The city's resurrection has partly come from tour operators offering fishing and sightseeing deep in the forest.

Now, the ayahuasca devotees are flowing in, searching for insight into their lives from a growing flock of local and foreign shamans, or medicine men. Tour operators say the potion -- and the ceremonies in which it is consumed -- has become a cornerstone of the local tourism industry.

"I'm the only tour operator in Iquitos who's never made a penny on ayahuasca," said William Grimes, a former soybean farmer from Indiana who has spent much of the past 12 years here.

Grimes said that some of those who initially came for the ayahuasca were drug users looking for an LSD-like high. But that quickly ended, Grimes said, and most who now come are seeking ayahuasca's medicinal properties and the experience of indigenous rituals.

"We're seeing people coming for three or four weeks at a time, going on special diets, staying in nice hotels, eating in nice restaurants and contributing to the economy," said Grimes, who owns Dawn on the Amazon Tours and Cruises. "I think it's good."

The visitors go to centers with names like the Temple of the Way of Light, Sachamama and the Yacu Puma Healing Center.