Aldo Ray metaphorically stumbles across mob money.
Rudy Bond is a sadist who makes a game out of killing his victims, making them believe there is a contest involved.
Brian Keith works with Rudy Bond, and is disgusted by him, till the sadist finally decides to try to kill him.
James Gregory is investigating all of this, and feels he is in over his head, and discusses his insecurities with his wife.
Sound familiar? Well, this was the original classic that McCarthy later went totally Hollywood formula with, but this one is the real deal.
Here, the bad guys are just as mortal as the good guys. They aren't "gods" or "demi gods", which is too much for the Beavis and Butthead brats who make up much of the first world right now.
This is a "mature" version, a version that isn't contrived, of three dimensional characters, or aptly put "credible characters in incredible circumstances", which is what separates the classic films from the disasters.
Much of this tale is told in flashback, and I'm no fan of flashbacks, but this film is a classic notwithstanding, because we find the characters so credible.