An elderly heiress is killed by her husband who wants control of her fortunes. What ensues is an all-out massacre.
From legendary director Mario Bava (who doubles as cinematographer) and legendary horror screenwriter Dardano Sacchetti comes a film that essentially everyone (including Sacchetti himself) accepts as the original slasher film, and being a precursor to "Friday the 13th". Some people have given "Black Christmas" credit for being the start of it all, and it does have more of the modern look, but "Bay" has so many stylistic flourishes and plot similarities that it has to be given credit.
Aside from the obvious concept of kids going into the woods and dying, we have some of the classic slasher themes: camera from the killer's point of view behind a tree, the double impalement of a couple making love. Bava was way ahead of the curve with this film, despite claims from Luca Palmerini that it is "predictable" or Jim Harper's calling it "blackly humorous". (Harper also points out the "flimsy story", but seems to be a fan of the film overall and recognizes its importance.)
As usual, the biggest critic is Howard Maxford (who never ceases to amaze me how he got a gig as a horror critic when he seems to hate them all). He tries to be complimentary by saying the film has "occasional pretensions to style", but has the overall opinion that Bava's work is "hard to sit through". Sure, it was not the most exciting film in the world, but if Maxford cannot relax for less than 90 minutes, he should not be a film reviewer.
I think the opening with the old woman in the wheelchair being hung had plenty of style and called to mind the later works of Argento (by which I mean the late 1970s). While the film as a whole has bland moments and your basic murder shots, this scene seals it for me as making the film more worthy of respect... Bava's influence on others is obvious (the entire Italian horror subgenre owes its existence to his films), but I think the finer points are often overlooked. Do not overlook this film.