In the mother of all giallo, director Mario Bava hacks and slashes his way into the birth of the slasher genre. There's a lot more at work here than your typical chainsaw-armed psycho, though: there's a special brand of nihilism at work. With a total of thirteen murders and five murderers, this is about more than just body count. You can read it, as I did, as a darkly funny horror film about the murderous nature of capitalism, as a typical slasher film (although you'd be missing a lot in that reading), or, as one guy has, as a story about the ecology rising up to protect itself. Any way you look at it, it's the pinnacle of the giallo genre, that unique brand of Italian suspense/horror films that made the careers of people like Bava and Dario Argento and, for better or worse, changed the face of horror films forever.

The film doesn't waste any time. A wheelchair-bound countess (Isa Miranda) is hanged in her home; her killer, who happens to be her husband (Giovanni Nuvoletti), is then stabbed to death and his body dragged away. There are plenty of suspects: there's Simon (Claudio Camaso), a local fisherman. There's a local bug collector (Leopoldo Trieste), who argues with Simon about killing. There's his fortune-telling wife (Laura Betti), who sees gloom and doom in her tarot cards. There's the slimy developer Ventura (Cristea Avram), who beds his secretary and has his sights set on turning the local bay, which was owned by the countess, into a resort town. And arriving late on the scene are the count's daughter Renata (Claudine Auger) and her husband Albert (Luigi Pistilli), who come to find their missing father and to take control of the deed to the bay so they can sell it to developers. Thrown into the mix is a quartet of attractive young people who break into a beach house for a marathon of sex and drugs and bad 1970s music.

There's very little attempt to develop any of the characters. We discover, for example, that Simon is the countess's illegitimate son, and, late in the film, we find out why the countess was killed. But most of the film is a string of grisly murders, done in the most stylistic and flashy manner imaginable. We later learn exactly why the string of murders happens the way it does, but it matters little. It's all about how they happen. Fans of the slasher genre will recognize many of the murders from Friday the 13th, Part 2, which "borrowed" many of them, including the wheelchair, the spear, and the machete. There's little motivation given, aside from greed and fear; "regular" people turn into vicious murderers, by chance or out of pique. It's a dark, depressing take on human nature, where nobody is more than a couple of steps from becoming a murderer. If it weren't so perfectly styled and paced, it would be way too much to watch.

There's an interesting, if rambling, discussion of this film on the IMDB message boards. A guy named "melvelit" claims that the true killer is not any of the various people who wield knives, hatchets, and spears, but the bay itself. The theory is that since the original title of the film is "Chain Reaction" ("Reazione a catena" in Italian), it is necessary to dig down to the beginning of the chain. That chain starts at the very beginning of the film, when a buzzing insect that serves as our point of view drops dead into the bay. From there, the trail of death climbs the food chain to kill the entire neighborhood, all of whom, with two exceptions, had the destruction of the bay's ecology in mind. The exceptions are the Countess, who is murdered because she won't sell, and whose death means the bay has to go into action to defend itself; and the bug collector, whose sin is talking about the bay's self-defense killings—and he's strangled with the instrument of his tattling. The four teenagers who are offed are not killed because they're having sex, which is the typical understanding (and it was mine too), but because they're the very type of people who, once the resort is open, would come and befoul the bay with their beer cans and bonfires. It's certainly an intriguing argument. After my single viewing, I can't really take issue with anything he said, except to point out that the bay should not have had anything against that initial bug that drops dead—but if the bug represents our point of view, perhaps the film is identifying us as part of the problem.

The acting isn't very good, and it's badly dubbed, which is typical for this kind of film—indeed, it's one of the charms of the genre. There's a problem with the sound on the DVD release: the dialog is all over the map in terms of volume, so you have to constantly adjust it, which can be annoying. The plot is both impossibly convoluted and ridiculously simple, which you'll realize as soon as you stop trying to figure it out. This is a film for a very small audience, and you know who you are. You'll see things that countless horror films have stolen, but unlike a lot of classic films that have been ripped off for years, this one holds up. It's a great example of how "style over substance" isn't necessarily a bad thing.