Scream Bloody Murder (1973)

"See what I do for you? I get you groceries and clothes and art stuff and kill people!"

This line, delivered with whiny earnestness and without a hint of irony or self-awareness, is likely to be one of several moments of script absurdity that stick with you, should you actually decide to sit down and watch this rather nasty little Oedipus riff.

It begins with a farmer stopping his tractor to tinker with the engine.  His son, who looks about 10 or 12, hops into the cab and proceeds to run his father over.  Which, given that the tractor has the acceleration and maneuverability of ... well, a tractor ... requires considerable stupidity - or perhaps just a death wish - on the part of the father.  Whatever it is, it runs in the family, because the kid manages to run over his own hand when dismounting from the tractor.

The kid - Matthew - gets packed off to a mental hospital and when next we see him he looks about 20 and is sporting an iron hook in place of his missing hand.  He's also very very angry that his mother's sent him a letter which indicates there is a new man in his life.

In fact, when Matthew arrives home in the next scene, it is to discover that his mother has just re-married.  Matthew's obviously unbalanced state on learning this - and a remark from his mother that the hospital didn't tell her he was being released - suggest that the young man is far from well, and probably left the facility without their knowledge.

Obsessed with "protecting" his mother's "purity", Matthew murders his step-father with an axe.  His mother discovers this however, and suffers a fatal accident in the ensuing struggle.  Matthew goes on the run, his sexual hang-ups leading him to accumulate an impressive body count in the process.

Ultimately, Matthew comes to fixate on a new woman; a bohemian hippy chick named Vera (played, in a nicely macabre touch, by the same woman that played his mother).  His efforts to "protect" her will ultimately lead to a deadly game of cat and mouse between the two.

Also known as The Captive Female, this odd little number has a weird mix of probably-unintentional humour and wholly intentional nastiness.  I doubt that's a combination with a broad range of appeal.