A Bay of Blood, AKA Twitch of the Death Nerve, is a 1971 Giallo film by Mario Bava. Designed as a comeback film after he lost his distribution deal with American International Pictures, Bava effectively created a film that has served as the blueprint for the Slasher genre of horror, with many of its sequences copied by other horror films (most notably Friday the 13th and Friday the 13th Part 2).
The film's plot is a convoluted Whodunnit as people begin dying left and right during the course of a long weekend at the lakeside home of an elderly heiress. There are multiple murderers at work, as a slew of shady characters (and a quartet of sex-obsessed teens) end up dying in horrific fashion. There is also a surprise ending that will shock you...
This film provides examples of:
- Anyone Can Die: And does.
- Asshole Victim: Pretty much everyone who dies except for the heiress, the teenagers, and the entomologist and his wife.
- Big Bad Ensemble: Simon, Renata, Albert, Frank, and Laura are all the killers in the main plot, while Count Donati kickstarts the plot by killing his wife in the prologue (then promptly being offed himself).
- Decoy Antagonist: Count Filippo Donati is introduced as the killer of his own wife, but he is just as quickly killed by Simon.
- Decoy Protagonist:
- The Contessa is the first character to appear, but she ends up with a snapped neck almost immediately after her introduction.
- After the Contessa's and Count's death scenes, the film introduces Ventura and Laura. They turn out to be some of the many antagonists in the movie.
- Deus ex Machina: Just when it looks like Albert and Renata would get away with their crimes, they get shot by their own kids.
- Dub Name Change: The English version alters many of the characters' names to sound more "Anglicized":
- Alberto -> Albert
- Simone -> Simon
- Paolo -> Paul
- Franco -> Frank
- Louise -> Brunhilde
- Sylvie -> Denise
- Luca -> Duke
- Roberto -> Bobby
- Don't Go in the Woods: Or swimming in the bay. Or in the cabin nearby. Or... anywhere, really. Just drive away.
- Eldritch Location: Similar to other offerings in the genre that the film helped inspire, the bay and its environs seem to have a malevolent, murderous influence on people, though this falls into the Maybe Magic, Maybe Mundane category.
- Even Evil Has Loved Ones: Renata is glad to have found her father's corpse before the cops because it would mean that her father's reputation wouldn't be besmirched.
- Everybody Did It: Downplayed, but there are six characters who have committed murders.
- Evil Versus Evil: This is what the main conflict over the rights to the bay comes down to: Ventura and Laura versus Albert and Renata with Simon as the third faction.
- Extremely Short Timespan: The majority of the action unfolds over a single day. It is not clear how much time elapses between the Contessa's death and the start of the main action, but it does not seem to be more than a few days.
- Gardening-Variety Weapon: Simon uses a billhook as his primary weapon for murdering people.
- Gorn: Comfortably Bava's goriest film which sickened audiences back in the day but is now seen as the forefather of the slasher genre.
- Gory Discretion Shot: Averted. The kills are lovingly photographed in detail.
- Greed: The underlying motivation which kills literally.
- He Knows Too Much: The reason the teenagers are killed is because one stumbled upon Donati's body in the bay, and the entomologist and his wife are killed by Albert and Renata because the former saw them kill Frank.
- Heel–Face Door-Slam: After Simon kills the secretary for the death of his mother, the heiress, it's revealed that he killed all the teenagers for finding Donati's body and made a deal to sell the bay in order to keep it a secret. He seems to show some remorse for his part in all this but is immediately killed by Albert.
- Hooks and Crooks: One character gets killed when a billhook catches her throat.
- I Just Shot Marvin in the Face: Renata and Albert end up being killed when their son shoots them with a double-barreled shotgun, without realizing that they are dead for real.
- It Gets Easier: At first, Albert is freaked out over his first kill, but he eventually gets over it even taking pride in it.
- Impaled with Extreme Prejudice: The two boffing kids and Simon.
- The Killer Becomes the Killed: The Count, Simon, Frank and his lover, and the greedy parents in the finale.
- Mind Screw: It can get confusing for the audience to figure out who did what, but the Flashbacks near the end explain the plot, allowing the audience to finally see the full picture.
- Out with a Bang: Two of the teenagers end up being skewered while they were doing the deed.
- Peek-a-Boo Corpse:
- The Count to one of the teen girls. She doesn't last long after it, though.
- Later combined with Mirror Scare when Renata goes to the bathroom, puts on the light and sees the pile of corpses behind her from the mirror.
- The Place: A Bay of Blood
- Red Herring: Paolo Fossati is suggested to be the killer of the teenagers as his wife Anna has trouble locating him after their deaths, and he mysteriously has a new cut on his hand when Anna finally finds him. It turns out that he is one of the few innocent characters in the movie.
- Sex Signals Death: Two kids. Impaled. But in this one the girl is on top.
- Wild Card: Simon is this to Frank and Laura as he throws a wrench into their plans after killing Filippo Donati. Frank does manage to blackmail him into joining their side, but Simon eventually betrays them after figuring out Frank and Laura were involved in the Contessa's murder. Despite this, Simon ends up dying to Albert.
- The X of Y: A Bay of Blood
- Youth Is Wasted on the Dumb: Some can say this of the four young people who stop for a quick death.
