I'd never heard of this and it proved a charming surprise. About a group of men who all find themselves exiled for various reasons to a Porvenir, Chile and are offered a chance to redeem themselves with some great financial recovery if they'll take on the hazardous mission of driving an unstable load of nitroglycerin through the jungle some 200+ miles.
It's surprisingly engaging, and the pacing - exposition - plot development - well, all at odds with current film-making fashion. But well done, and the trucks they're given to accomplish their mission rival anything you saw in "Fury Road".
The reason - most probably - you never heard of it was that it was released in 1977 and immediately overshadowed by Star Wars.
William Friedkin also directed the "The French Connection" and "The Exorcist", Roy Scheider you'll recognize as the small-town sheriff from "Jaws".