When former special forces demolitions expert Mickey Grosman led a group of amateur adventurers through South America's Amazon in 2012, a terrifying nightmare unfolded.

Marketed as a charity trek for cancer awareness, participants were to be part of a 5,000-mile (about 8,000km) expedition across the continent through the deepest parts of the Amazon jungle. About 24 people started the trek. Only one claimed to have made it to the end...

A series of events, from kidnapping, prison escapes, and a missing person, turned an already challenging expedition into a near-constant struggle for survival.

Using over 700 hours of archival footage from the trip, the Discovery Channel produced a limited docuseries called Expedition from Hell: The Lost Tapes documenting the group's expedition through the Amazon led by a charismatic guide with unclear motives.

"Pulled from hundreds of hours of footage, every episode of this compelling docuseries includes terrifying obstacles endured by those who chose to join the expedition," said Howard Lee, President of Discovery Networks.

"As we dug deeper to understand the motives behind those who took part in this doomed adventure, even we were surprised by what we saw."

The series uncovers brand new revelations that shocked even those who were alongside Grosman during the ill-fated adventure.

Ahead of the official release of the series, documentary makers Erin Gamble and David Freid told the Daily Mail there were some parts of the footage that were too horrific to include in the final cut.

"You cannot go from one coast to the other across the Amazon jungle unless you are nuts. It's very dangerous," they said.

Discovery Africa describes Expedition from Hell: The Lost Tapes as the "unravelling of a journey filled with danger, deception, and survival against all odds."

Expedition from Hell: The Lost Tapes premieres on Discovery Africa on May 22 at 8 pm.