A Bay of Blood

• The body count is 13, and the script was assembled backward from it. Bava's writers conceived the murders first as isolated set-pieces with no plan for how they'd connect, then built the inheritance plot around them, which is why it plays as a kill reel with a story bolted on rather than a mystery (source: Wikipedia, en.wikipedia.org/wiki/A_Bay_of_Blood).
• Friday the 13th Part 2 lifted the double-spear kill, the couple skewered together mid-embrace in bed, nearly shot-for-shot, and the first Friday the 13th echoes the billhook-to-the-face death where a victim opens a door straight into the blade (source: ScreenRant, screenrant.com/italian-horror-a-bay-of-blood-inspired-friday-the-13th).
• The gore was built by Carlo Rambaldi, the effects man who'd go on to Oscar-winning work on Alien and E.T. (plus a special-achievement Academy Award for 1976's King Kong). Slasher fans owe his early splatter the same debt sci-fi fans owe his creatures.
• The budget was bottom-of-the-barrel, so Bava shot it himself as his own cinematographer and rolled his prowling killer-POV tracking shots on a child's toy wagon (sources: Wikipedia en.wikipedia.org/wiki/A_Bay_of_Blood and Dread Central, dreadcentral.com/news/341546).
• Britain's censors put it on the Video Nasty DPP list and prosecuted it under the Obscene Publications Act; it didn't reach UK home video legitimately until 1994 with 43 seconds hacked out, and wasn't passed fully uncut until 2010 (source: Video Nasty Files list, letterboxd.com/theportman/list/the-video-nasty-files).
• Claudine Auger — Domino, the Bond girl in Thunderball (1965) — turns up here as Renata, one of the heirs circling the bay; the murdered countess at the center of it all is played by Isa Miranda.

The ending is the whole point, not a twist. After every adult schemes and murders for the bayside property, the two surviving heirs are gunned down by their own small children, who grab a real shotgun thinking it's a toy and treat the corpses as a game of 'playing dead.' Read it as Bava's verdict on greed: the violence is inherited like the land, passed down to kids who don't even understand they've done it. The original working-title gag, the girl nearly saying 'that'll teach them to be bad,' makes the moral-fable read explicit.

There is no killer to unmask because the bay itself is the antagonist. With at least half a dozen murderers and no single POV stalker holding the film together, fans argue the real subject is the property and the ecology around it, the Italian title Ecologia del delitto (Ecology of Crime) being the tell. Every death feeds the next claim, a closed food chain where the location consumes everyone who covets it.

It's secretly a comedy wearing a slasher's skin. The dark-humor camp, the self-aware overkill, Stelvio Cipriani's almost playful score under the carnage, and that punchline finale lead many to argue Bava is mocking the murder-mystery and the body-count formula a full decade before the slashers he'd inspire took it dead seriously. The kills aren't suspense, they're escalating sick jokes, and the kids-with-the-shotgun ending is the cackle that proves it.

A dead countess. A waterfront worth killing for. And a cast of heirs, schemers and trespassers who keep arriving at the bay just in time to die. Bava doesn't bother with a detective or a single masked killer here. Everybody's guilty, everybody's a target, and the bodies stack up by billhook, spear, machete and noose until the last claimant standing thinks they've won. Then two kids find a shotgun. Cold, gorgeous, mean as a snakebite, and built entirely around the killing.