Thanks to his orgiastic feasts of Gothic horror and comic book pop art, no one ever described Mario Bava as a restrained director. However, few could have anticipated the unbridled ferocity of his trendsetting 1971 shocker, Reazione a catena ("Chain Reaction"), which turned up in Europe under such titles as Antefatto, A Bay of Blood, and Ecologia del delitto before terrorizing U.S. drive-ins for years as Last House - Part II and, most unforgettably, Twitch of the Death Nerve. Here Bava tears the horror genre apart from the ground up, dispensing with linear plotting or realistic characterization in favor of a mechanical, devious (and sometimes blackly hilarious) catalog of murders, all served up with the tricky, sumptuous photography which gives his films their unforgettable artistic stamp. Even more than his earlier Blood and Black Lace, this is the body count movie par excellence.

In the haunting and very surprising opening, an elderly countess (Miranda) stares sadly through a rain-dappled window at her property surrounding a remote bay. Suddenly her wheelchair-bound body is seized up by a lariat, hoisting her back and choking the life from her throat. Her assailant nonchalantly steps outside and surveys his handiwork, then returns inside... only to get a nasty surprise himself. Thus begins a mad, scurrying patchwork of fragmented narratives in which various residents and visitors become victim or predator, or sometimes both at once, in order to claim this valuable chunk of property. Watch and learn the fates of four partying youths, a Medusa-haired tarot freak (A Hatchet for the Honeymoon's Betti), the sinister squid-hunting local Simon (Camoso), and visiting married couple Renata (Thunderball's Auger) and Albert (giallo regular Pistilli). The solution to this bloody tangle of lives and motives will certainly startle you and probably provoke a sick chuckle as well.

Though rarely acknowledged by the mainstream press, A Bay of Blood is now regarded by most of the horror community as the progenitor of the slasher wave from the '80s (with Steve Miner's Friday the 13th Part II suffering the most direct accusations of, ahem, "direct inspiration"). However, Bava's film is a more clever, subtle, and visually sumptuous affair than your standard stalk and kill yarn; even with limited means he conjures up a swirling symphony of poetic images, from the rippling textures of the bay waters (even when strewn with corpses) to the macabre ocher glow behind a glass door during Renata's standout victim scene. The cheeky gore effects still shock today, including an unforgettable facial machete application, a unique shish-kebab variation, and a startling beheading, all laced with some '70s-styled helpings of nudity and sex. Stelvio Cipriani's deft score wavers between beautifully sustained and creepy beat rhythms (the main titles in particular) to the hilarious upbeat pop pastorale of the end credits (later recycled for Francois Ozon's Potiche!), while the actors all seem to be having a ball before turning up as lambs to the slaughter. (Genre fans, look for an appearance by little Nicoletta Elmi, who also turned up in Deep Red, Flesh for Frankenstein, and Bava's Baron Blood, among many others.)

Apart from tangling with British censors during the video nasty debacle (leading to a censored U.K. VHS release from Redemption), this very gory film has somehow managed to avoid censorship in most territories and has been presented uncut in virtually every country in which it has been released (including a memorable stint on VHS from Gorgon with wonderfully grotesque cover art). Discounting a hideous budget release from Simitar, the first legitimate DVD of this film (packaged as Twitch of the Death Nerve but containing the onscreen title of A Bay of Blood) was released by Image in 2001. Unfortunately the English mono soundtrack suffered from heavy distortion during louder sounds and was often very harsh on the ear, making the film a chore t to sit through. That disc also includes the theatrical trailer under the alternate title of Carnage (first seen on home video as part of Mad Ron's Prevues from Hell), along with the standard Bava bio and photo gallery, a special tongue-in-cheek "Murder Menu" leading to each death scene, a couple of outrageous radio spots, and thorough, illuminating liner notes from Tim Lucas, anticipating his more extensive coverage to come in his essential Bava book. Lucas also managed to return to the film for an audio commentary when the rights passed over to Anchor Bay, leading to another DVD release in 2007 as part of their second Mario Bava collection (with a standalone release issued soon after). The commentary explains the production details in depth and pointing out little facts about each of the cast members, the memorable shooting location, and Bava's own humorous touches in many scenes. On the other hand, it's also somewhat halting in delivery and features an unusual number of errors starting off the bat by crediting Cipriani as the composer of Roy Colt and Winchester Jack. That transfer looked very similar to the Image one (i.e., very colorful, free of damage, and perfectly framed), with significantly improved audio as well. The radio spots and trailer were carried over along with a stills and poster gallery. Released in Italy almost concurrently from Raro Video was another DVD containing the Italian cut of the film (with optional English subtitles), a 19m47s featurette with Lamberto Bava, screenwriter Dardano Sacchetti, CSC director Steve Della Casa, still photographer Franco Vitale, Roy Bava, biographer Alberto Pezzotta, and Joe Dante called "The Art of Crime," and the trailer. Though the film was geared for an English audience (even with dubbing, most of the actors were clearly speaking English), the Italian cut features several alternate takes and a few variations in its editing. This isn't a matter of one version really being more "complete" than the other; it's simply a different assembly with a few extended in and out points and some alternate shots here and there, but it's a nice option for completists.

In 2010, A Bay of Blood became the very first Bava film to hit Blu-ray courtesy of Arrow in the U.K., carrying over the commentary and radio spots while adding the Italian cut (in standard def with English subs), a video appreciation of the film and Bava in general from Joe Dante (12m26s) featuring one of the longest intros you'll ever see, the Trailers from Hell version of the trailer with Edgar Wright, "The Giallo Gems of Dardano Sacchetti" (a fun 33m10s interview with the horror/thriller screenwriter), and "Shooting a Spaghetti Splatter Classic" (a 21m16s interview with assistant cameraman Gianlorenzo Battaglia). Unfortunately the release stumbles when it comes to the feature itself, as the HD master suffers from highly desaturated colors (with red almost nonexistent) and milky black levels. It's not hideous by any means, but it certainly felt a whole lot less like a Bava film and left much room for improvement.

Thankfully the 2013 Blu-ray release from Kino Lorber (with a DVD reissue at the same time) improved things image-wise with better color timing bringing out the spooky blues of the night scenes and the rampant gold and crimson flourishes in the art direction during interior shots. There's also a pretty substantial amount of additional image information on the top, bottom, and right sides, too. It's really no contest. The LPCM mono track sounds exceptionally sharp and clean for the most part, though it takes a major quality dive in the third reel (especially around the 45-minute mark) where it becomes essentially unlistenable for several minutes. The same Tim Lucas audio commentary is also included, thankfully, after the odd speed bump of the Kino Bava disc just before this one, Black Sabbath, as well as the alternate Italian cut (again in standard def and English subtitled). Finally the disc closes out with the Carnage trailer and bonus ones for Black Sunday, Baron Blood, Lisa and the Devil, and House of Exorcism. A subsequent French Blu-ray used the same scans of the English and Italian versions as the Arrow release, while the French-only extras include a scene analysis by Mathieu Macheret (20m22s) and interviews about the film with Gerard Lenne (25m1s) and Nicolas Stanzick (25m25s). In the middle of 2025, Scream Factory issued a 12-disc Blu-ray Mario Bava set that was a steep downgrade for almost all the films in the set with far fewer bonus features and inferior presentations (especially inexcusable burned-in subtitles for films like Four Times That Night and Kidnapped). For what it's worth, the Bay of Blood Blu-ray features the same scan of the English version as the Kino plus four commentaries by Meagan Navarro, Richard Newby and Reyna Cervantes, Karen Stollzow, Matt Baxter, and Blake Smith, and Bill Bria and Ashley Coffin.

In 2026, Severin Films presented the first UHD incarnation of the film as part of a five-disc(!) set originally announced for Black Friday of 2025. Both the first UHD and Blu-ray are devoted to a new scan of the English-language version from the original negative for the first time, with radical improvements in both color timing and especially audio quality with the DTS-HD MA 2.0 English mono track (with optional English SDH subtitles). The UHD in particular does a vastly superior job of handling the magic hour outdoor scenes which now have a beautiful dusky quality you couldn't see before, and detail throughout is impressive. The framing does shift here with less on the sides and bottom. Tim Lucas provides a completely new, revised audio commentary here that also makes for a significant upgrade over his older track, fixing all the earlier snafus and delivering a more confident flow of information including considerable material that's come to light since the publication of his book. The U.S. Carnage trailer is also included on both discs, while the Blu-ray adds more extras starting with "All About My Father" (14m30s) with Lamberto Bava chatting about the lessons he learned on his dad's sets about life itself and filmmaking. In "It Was Just a Children's Game" (13m22s), actress Nicoletta Elmi remembers getting into child acting and modeling, being called in for bigger gigs once she got an agent, and the flurry of genre roles she had in quick succession including Who Saw Her Die?, this film, Baron Blood, and Deep Red. In "Lens of Blood" (27m57s), assistant camera operator Gianlorenzo Battaglia is interviewed about working on Five Dolls for an August Moon before this film, Bava's creative and playful working process, and the distinctive process of how shots were lit to always convey a sense of depth. Finally in "That Will Teach Them To Be Bad" (46m20s), Stephen Thrower dives perceptively into the film's complex title changes since its inception, the distribution history, parallels to other films around that time including a shared touch with Straw Dogs, the body count mechanics, and the film's future impact on the horror genre.

The second UHD and second Blu-ray are devoted to the film's Italian versions-- yep, you get two of them here. The familiar general release Reazione a catena version is here with a fresh scan from actual film material for the first time in decades, looking great here and much better than the ragged SD option we've had for so long. However, you also get the elusive initial Ecologia del delitto version (both have end credits unlike the English one) which makes three quick but crucial changes to the final scene including a very different line of dialogue for Elmi, no dialogue before the shotgun blasts (which makes it play a lot better), and a small burst of funereal music. It's quite wild to see how much darker this plays than the revised Italian and only English versions. The Italian trailer is also included, with the Blu-ray adding more extras kicking off with "Hallmark Of Horror: Carnage, Death Nerves & Last House Part II" (19m35s) with Stephen R. Bissette covering the colorful and lurid history of the film's U.S. distributor including much ballyhoo for titles like this one, Mark of the Devil and Last House on the Left. Bissette was also the locator of an original Hallmark Carnage barf bag owned by Robert Deveau which has been thoughtfully reproduced when you buy the limited edition directly from the label. The "Art of Crime" featurette from the Raro DVD is ported over here, plus archival interviews with Lamberto Bava and Sacchetti, "(Sittin' On) The Blood of the Bay" (22m19s) and "13 Ways to Die" (21m9s), giving broad overviews of the film's importance to their careers and its evolution to the final version we have today. "Bava and the Grindhouse" is a formal title given to the Joe Dante interview from the Arrow release, followed by a quick 2025 Lamberto Bava intro to the film (40s) from the Severin Super-Shock 2025 fest, storyboard comparisons (2m15s), and 1m31s of Twitch of the Death Nerve radio spots. The limited edition also comes in an exclusive slipcase plus the soundtrack CD featuring Cipriani's entire glorious score.

Severin Films (UHD) (English Version)



Severin Films (UHD) (Italian Version)



Severin Films (Blu-ray) (English Version)



Kino Lorber (Blu-ray) (English Version)



Kino Lorber (Blu-ray) (Italian Version)



Arrow Video (Blu-ray)



Scream Factory (Blu-ray)



ESC Editions (Blu-ray)

Updated review on March 1, 2026