Man, the upbeat disco theme tune truly sets you up for the grim turn-of-the-century slave plantation plot.
Somewhere in Brazil, an uppity jerk rules a rubber plantation full of slaves made up of the local tribesmen, wanderers that have been grabbed, and people the guy just plain hates. This includes Fabio Testi, whose wife was murdered by the jerk and whose kid died on the death march to the plantation. Then there's Howard, who cheated on the plantation owner's wife (Agnostina Belli). Agnostina herself is the newest member of staff, thrown in a hut as the slaves pounce on her.
These three, plus one Spanish guy playing a tribeman, all escape and the bulk of the film details their journey through the jungle to Ecuador...then back again as they change their mind.
It's kind of like Spartacus: Rubber Plant Slave Edition, as our crew gather more freed slaves to take on The Man. Due to the grim start where Agnostina Belli is thrown to the slaves as a plaything, I thought this was going to one of those depressing deals, but the rest is straightforward action. They don't even harm any animals, judging by them having the fakest looking spider ever in there.
Loads of shootouts and jungle travelling keep things going as our heroes turn the tables on the slavemasters, plus you get a bizarre sub-plot involving someone stealing rubber plant seeds to destroy the industry that pretty much all happens off-screen. Flroinda Balken turns up as the rich wife of one of these guys and gives a moving speech about the horrors of slavery.
I guess a lot of people where expecting something much nastier considering the films released around this time, but as an action film its pretty satisfying.